As promised, here comes the next backtrace. Hope this helps.
#0 MOZ_CrashOOL (aLine=3424, aReason=0x55555556ca10 "(run->regs_mask[elm] & (1U << bit)) == 0") at /build/firefox-esr-KT8g23/firefox-esr-52.2.0esr/mfbt/Assertions.cpp:33 No locals. #1 0x0000555555567c1d in arena_dalloc_small (mapelm=<optimized out>, ptr=<optimized out>, chunk=<optimized out>, arena=<optimized out>) at /build/firefox-esr-KT8g23/firefox-esr-52.2.0esr/memory/mozjemalloc/jemalloc.c:4660 run_pageind = <optimized out> run_mapelm = <optimized out> run = <optimized out> bin = <optimized out> size = <optimized out> #2 arena_dalloc (ptr=<optimized out>, offset=<optimized out>) at /build/firefox-esr-KT8g23/firefox-esr-52.2.0esr/memory/mozjemalloc/jemalloc.c:4728 chunk = <optimized out> arena = 0x7ffff6c00040 pageind = <optimized out> mapelm = <optimized out> #3 0x00007fffebb16423 in js_free (p=<optimized out>) at /build/firefox-esr-KT8g23/firefox-esr-52.2.0esr/build-browser/dist/include/js/Utility.h:257 No locals. #4 js::FreeOp::free_ (this=0x7fffde7f9ce0, p=<optimized out>) at /build/firefox-esr-KT8g23/firefox-esr-52.2.0esr/js/src/vm/Runtime.h:1371 No locals. #5 JSObject::finalize (fop=0x7fffde7f9ce0, this=<optimized out>) at /build/firefox-esr-KT8g23/firefox-esr-52.2.0esr/js/src/jsobjinlines.h:93 nobj = 0x7fff2051e040 #6 js::gc::Arena::finalize<JSObject> (this=this@entry=0x7fff2051e000, fop=fop@entry=0x7fffde7f9ce0, thingKind=thingKind@entry=js::gc::AllocKind::OBJECT8_BACKGROUND, thingSize=thingSize@entry=96) at /build/firefox-esr-KT8g23/firefox-esr-52.2.0esr/js/src/jsgc.cpp:457 i = {<js::gc::ArenaCellIterImpl> = {firstThingOffset = 64, thingSize = 64, arenaAddr = 0x7fff2051e000, span = {first = 39538, last = 6}, thing = 64, traceKind = JS::TraceKind::Object, needsBarrier = false, initialized = {<No data fields>}}, <No data fields>} firstThingOrSuccessorOfLastMarkedThing = 64 lastThing = 4000 newListHead = {first = 64, last = 1792} newListTail = 0x7fffde7f8adc nmarked = 0 lastMarkedThing = <optimized out> #7 0x00007fffebb16d53 in FinalizeTypedArenas<JSObject> (fop=0x7fffde7f9ce0, src=0x7fffde7f8bf8, dest=..., thingKind=thingKind@entry=js::gc::AllocKind::OBJECT8_BACKGROUND, budget=..., keepArenas=js::gc::ArenaLists::KEEP_ARENAS) at /build/firefox-esr-KT8g23/firefox-esr-52.2.0esr/js/src/jsgc.cpp:515 arena = <optimized out> nmarked = <optimized out> nfree = <optimized out> maybeLock = {mIsSome = false, mStorage = {u = { mBytes = "\000VVUUU\000\000\b\017\220\241\377\177\000\000 \001\300\366\377\177\000", mDummy = 93824992302592}}} #8 0x00007fffebb187e4 in FinalizeArenas (keepArenas=js::gc::ArenaLists::KEEP_ARENAS, budget=..., thingKind=<optimized out>, dest=..., src=0x7fffde7f8bf8, fop=0x7fff526d4000) at /build/firefox-esr-KT8g23/firefox-esr-52.2.0esr/js/src/jsgc.cpp:549 No locals. #9 js::gc::ArenaLists::backgroundFinalize (fop=fop@entry=0x7fffde7f9ce0, listHead=<optimized out>, empty=empty@entry=0x7fffde7f9c98) at /build/firefox-esr-KT8g23/firefox-esr-52.2.0esr/js/src/jsgc.cpp:2801 zone = 0x7fff526d4000 finalizedSorted = {static MinThingSize = 16, static MaxThingsPerArena = 253, thingsPerArena_ = 42, segments = {{ head = 0x7fff9eb9c000, tailp = 0x7fff14376010}, {head = 0x7fff538ec000, tailp = 0x7fff2c618010}, {head = 0x7fff6ceb6000, tailp = 0x7fff14bec010}, {head = 0x7fff7c819000, tailp = 0x7fff5506a010}, {head = 0x7fff7ff6e000, tailp = 0x7fff14251010}, { head = 0x7fff23372000, tailp = 0x7fff3f5b3010}, {head = 0x7fff53810000, tailp = 0x7ffee3f8b010}, {head = 0x7fff2a874000, tailp = 0x7fff143ae010}, {head = 0x7fff5376e000, tailp = 0x7fff77020010}, {head = 0x7fff1826c000, tailp = 0x7fff14c46010}, { head = 0x7fff53813000, tailp = 0x7fff7c97d010}, {head = 0x7fff182ce000, tailp = 0x7ffee24bf010}, {head = 0x7fff34f30000, tailp = 0x7fff3f594010}, {head = 0x7fff1a3c8000, tailp = 0x7fff204cc010}, {head = 0x7fff1a351000, tailp = 0x7fff54730010}, { head = 0x7fff18233000, tailp = 0x7fff3acd5010}, {head = 0x7fff182c9000, tailp = 0x7fff6d831010}, {head = 0x7fff14863000, tailp = 0x7ffef0e2f010}, {head = 0x7fff182cd000, tailp = 0x7fff14b4a010}, {head = 0x7fff1a3e9000, tailp = 0x7ffee21e6010}, { head = 0x7fff182c5000, tailp = 0x7fff1b091010}, {head = 0x7fff16de3000, tailp = 0x7fff2be40010}, {head = 0x7fff1f3eb000, tailp = 0x7fff2396b010}, {head = 0x7fff182d4000, tailp = 0x7fff16b29010}, {head = 0x7fff18264000, tailp = 0x7fff1436a010}, { head = 0x7fff2bfa2000, tailp = 0x7fff22e44010}, {head = 0x7fff1e768000, tailp = 0x7fffb2fa2010}, {head = 0x7fff182a3000, tailp = 0x7fff22d45010}, {head = 0x7fff1a3f7000, tailp = 0x7fff14a9e010}, {head = 0x7fff14adb000, tailp = 0x7fff14aad010}, { head = 0x7fff1a34a000, tailp = 0x7fffc21ad010}, {head = 0x7fff1429d000, tailp = 0x7fff23996010}, {head = 0x7fff1a34b000, tailp = 0x7fff14a86010}, {head = 0x7fff495a1000, tailp = 0x7fff23950010}, {head = 0x7fff1a3ee000, tailp = 0x7fff1b14b010}, { head = 0x7fff1a3ad000, tailp = 0x7fff1fad2010}, {head = 0x7fff1ce3d000, tailp = 0x7fff148f6010}, {head = 0x7fff1a353000, tailp = 0x7fff1f39e010}, {head = 0x7fff16dd0000, tailp = 0x7fff53826010}, {head = 0x7fff14c79000, tailp = 0x7fff16e69010}, { head = 0x7fff16c63000, tailp = 0x7fff7fc22010}, {head = 0x7fff1412f000, tailp = 0x7fff32ed2010}, {head = 0x7fff182a5000, tailp = 0x7ffee3f67010}, {head = 0x7fff16c04000, tailp = 0x7fff1293b010}, {head = 0x7fff0c978000, tailp = 0x7fff0c98c010}, { head = 0x7fff230ef000, tailp = 0x7fff14cc6010}, {head = 0x7fffb2f77000, tailp = 0x7fff1cd7d010}, {head = 0x7fff22eb0000, tailp = 0x7fff0f3ef010}, {head = 0x7fff6ea3b000, tailp = 0x7fff5a6d6010}, {head = 0x7fff20469000, tailp = 0x7fff0f318010}, { head = 0x7fff0f33c000, tailp = 0x7ffee2439010}, {head = 0x7ffef0e61000, tailp = 0x7fff56077010}, {head = 0x7fff55bcf000, tailp = 0x7ffee240f010}, {head = 0x7fff14947000, tailp = 0x7fff0c9d8010}, {head = 0x7fff3d8da000, tailp = 0x7fff1a8f2010}, { head = 0x7fff495a9000, tailp = 0x7ffee25a5010}, {head = 0x7fff14256000, tailp = 0x7fff1a8ec010}, {head = 0x7fff2a86b000, tailp = 0x7ffee2582010}, {head = 0x7fffb79ce000, tailp = 0x7ffee2435010}, {head = 0x7fff5a6ec000, tailp = 0x7fff32e0b010}, { head = 0x7fff55bad000, tailp = 0x7fff0f36f010}, {head = 0x7fff0c973000, tailp = 0x7ffee2587010}, {head = 0x7fff0f345000, tailp = 0x7fff14ced010}, {head = 0x0, tailp = 0x7fffde7f9048}, {head = 0x7fffb2f59000, tailp = 0x7fff1faa3010}, { head = 0x7fff9b64f000, tailp = 0x7fff64edc010}, {head = 0x7fff1f642000, tailp = 0x7fffb253e010}, {head = 0x7fff56096000, tailp = 0x7fff4dfd4010}, {head = 0x7fff20609000, tailp = 0x7fff183c9010}, {head = 0x7fff204b5000, tailp = 0x7fff6d87d010}, { head = 0x7fff1a341000, tailp = 0x7fffb5d00010}, {head = 0x7fffb2f3c000, tailp = 0x7fff4df6e010}, {head = 0x7fff23aee000, tailp = 0x7fff20644010}, {head = 0x7fff2346a000, tailp = 0x7fff3f5d2010}, {head = 0x7fff77019000, tailp = 0x7fff1f289010}, { head = 0x7fff14cb6000, tailp = 0x7fff2827f010}, {head = 0x7fff3d8b9000, tailp = 0x7fff52bb8010}, {head = 0x7fff14110000, tailp = 0x7fffb9111010}, {head = 0x7fffb9106000, tailp = 0x7fff1f2e3010}, {head = 0x7fff1e65f000, tailp = 0x7fff5384e010}, { head = 0x7fff23a04000, tailp = 0x7fff2c645010}, {head = 0x7fff1e7f8000, tailp = 0x7fffb9754010}, {head = 0x7fff2c13f000, tailp = 0x7fff2be53010}, {head = 0x7fff3d8d5000, tailp = 0x7fff55b7c010}, {head = 0x0, tailp = 0x7fffde7f9198}, { head = 0x0, tailp = 0x7fffde7f91a8}, {head = 0x0, tailp = 0x7fffde7f91b8}, {head = 0x7fff230e5000, tailp = 0x7fff560eb010}, {head = 0x0, tailp = 0x7fffde7f91d8}, {head = 0x7fff4d5cf000, tailp = 0x7fff4d5cf010}, {head = 0x0, tailp = 0x7fffde7f91f8}, { head = 0x7fff1a323000, tailp = 0x7fff18393010}, {head = 0x0, tailp = 0x7fffde7f9218}, {head = 0x0, tailp = 0x7fffde7f9228}, {head = 0x0, tailp = 0x7fffde7f9238}, {head = 0x7fff16ccf000, tailp = 0x7ffee3f56010}, {head = 0x7fff148ab000, tailp = 0x7fff70f67010}, {head = 0x7fff28262000, tailp = 0x7fff28262010}, {head = 0x7fff2a85f000, tailp = 0x7fff204b6010}, { head = 0x0, tailp = 0x7fffde7f9288}, {head = 0x7fff0b076000, tailp = 0x7fff46b46010}, {head = 0x0, tailp = 0x7fffde7f92a8}, {head = 0x7fff2bff8000, tailp = 0x7fff2bff8010}, {head = 0x0, tailp = 0x7fffde7f92c8}, {head = 0x7ffee21f1000, tailp = 0x7ffee21f1010}, {head = 0x0, tailp = 0x7fffde7f92e8}, {head = 0x0, tailp = 0x7fffde7f92f8}, {head = 0x0, tailp = 0x7fffde7f9308}, {head = 0x7fff97a8c000, tailp = 0x7fff97a8c010}, {head = 0x7fffc2168000, tailp = 0x7fffc2168010}, { head = 0x0, tailp = 0x7fffde7f9338}, {head = 0x7fff1a390000, tailp = 0x7fff1a390010}, {head = 0x0, tailp = 0x7fffde7f9358}, {head = 0x0, tailp = 0x7fffde7f9368}, {head = 0x7fff32e49000, tailp = 0x7fff32e49010}, {head = 0x7fff3d8e6000, tailp = 0x7ffee2102010}, {head = 0x7ffee3f3d000, tailp = 0x7fff32e86010}, {head = 0x7fff14c44000, tailp = 0x7fff14c44010}, { head = 0x7fff3acc7000, tailp = 0x7fff3acc7010}, {head = 0x7fff32e72000, tailp = 0x7fff32e72010}, {head = 0x0, tailp = 0x7fffde7f93d8}, {head = 0x0, tailp = 0x7fffde7f93e8}, {head = 0x0, tailp = 0x7fffde7f93f8}, { head = 0x7fff14c5c000, tailp = 0x7fff14c5c010}, {head = 0x0, tailp = 0x7fffde7f9418}, {head = 0x7fff5600a000, tailp = 0x7fff32eb1010}, {head = 0x0, tailp = 0x7fffde7f9438}, {head = 0x0, tailp = 0x7fff53581910}, { head = 0x7fff53581970, tailp = 0x21}, {head = 0x7fffde7f9480, tailp = 0x0}, {head = 0x4, tailp = 0x7fff00000020}, { head = 0x0, tailp = 0x7fffde7f94a8}, {head = 0x0, tailp = 0x4}, {head = 0x0, tailp = 0x7fffde7f94a8}, {head = 0x28, tailp = 0x7ffeebbb2c00}, {head = 0x0, tailp = 0x40}, {head = 0x0, tailp = 0xde7f9401}, {head = 0x7ffef417ef80, tailp = 0x7fff535ae008}, {head = 0x0, tailp = 0x1de7f9401}, {head = 0x7ffef417ef80, tailp = 0x7fff535adfe8}, {head = 0x0, tailp = 0x2de7f9501}, {head = 0x7ffef417ef80, tailp = 0x7fff535ae068}, {head = 0x0, tailp = 0x3de7f9501}, { head = 0x7ffef417ef80, tailp = 0x7fff535adf48}, {head = 0x0, tailp = 0x4de7f9500}, {head = 0x7ffef417ef80, tailp = 0x0}, { head = 0x0, tailp = 0x5de7f9501}, {head = 0x7ffef417ef80, tailp = 0x7fff535adee8}, {head = 0x0, tailp = 0x6de7f9501}, { head = 0x7ffef417ef80, tailp = 0x7fff535ae028}, {head = 0x0, tailp = 0x7de7f9501}, {head = 0x7ffef417ef80, tailp = 0x7fff535ae048}, {head = 0x0, tailp = 0x8de7f9501}, {head = 0x7ffef417ef80, tailp = 0x7fff53585848}, {head = 0x0, tailp = 0x9de7f9501}, {head = 0x7ffef417ef80, tailp = 0x7fff535858a8}, {head = 0x0, tailp = 0xade7f9601}, { head = 0x7ffef417ef80, tailp = 0x7fff53585908}, {head = 0x0, tailp = 0xbde7f9600}, {head = 0x7ffef417ef80, tailp = 0x0}, { head = 0x0, tailp = 0xcde7f9a01}, {head = 0x7ffef417ef80, tailp = 0x7fff53585968}, {head = 0x0, tailp = 0xd00000001}, { head = 0x7ffef417ef80, tailp = 0x7fff535859c8}, {head = 0x0, tailp = 0xede7f9601}, {head = 0x7ffef417ef80, tailp = 0x7fff53585a28}, {head = 0x0, tailp = 0xf00000001}, {head = 0x7ffef417ef80, tailp = 0x7fff53585a88}, {head = 0x0, tailp = 0x10de7f9801}, {head = 0x7ffef417ef80, tailp = 0x7fff53585ae8}, {head = 0x0, tailp = 0x11de7f9b01}, { head = 0x7ffef417ef80, tailp = 0x7fff53585b48}, {head = 0x0, tailp = 0x1200000001}, {head = 0x7ffef417ef80, tailp = 0x7fff53585ba8}, {head = 0x0, tailp = 0x13531aee01}, {head = 0x7ffef417ef80, tailp = 0x7fff53585c08}, {head = 0x0, tailp = 0x1400000001}, {head = 0x7ffef417ef80, tailp = 0x7fff53585c68}, {head = 0x0, tailp = 0x1500000001}, { head = 0x7ffef417ef80, tailp = 0x7fff53585cc8}, {head = 0x0, tailp = 0x16531ae001}, {head = 0x7ffef417ef80, tailp = 0x7fff53585d28}, {head = 0x0, tailp = 0x17531ae001}, {head = 0x7ffef417ef80, tailp = 0x7fff53585d88}, {head = 0x0, tailp = 0x18531b4701}, {head = 0x7ffef417ef80, tailp = 0x7fff53585de8}, {head = 0x0, tailp = 0x1900000001}, { head = 0x7ffef417ef80, tailp = 0x7fff53585e48}, {head = 0x0, tailp = 0x1a00000001}, {head = 0x7ffef417ef80, tailp = 0x7fff53585ea8}, {head = 0x0, tailp = 0x1b531afd01}, {head = 0x7ffef417ef80, tailp = 0x7fff53585f08}, { head = 0x5555555679cb <arena_dalloc+115>, tailp = 0x1cde7f9801}, {head = 0x7ffef4100000, tailp = 0x7fff53585f68}, { head = 0x80, tailp = 0x40}, {head = 0x7ffef417ebc0, tailp = 0x7fff0e25b880}, {head = 0x7ffef4100000, tailp = 0x7ffeee1e3c50}, {head = 0x555555569502 <realloc+962>, tailp = 0x7fffde7f9930}, {head = 0x7fffeba35c1c <js::jit::RValueAllocation::writePayload(js::jit::CompactBufferWriter&, js::jit::RValueAllocation::PayloadType, js::jit::RValueAllocation::Payload)+172>, tailp = 0x7ffeee1e3c38}, {head = 0x5555555679cb <arena_dalloc+115>, tailp = 0x7fffde7f99c0}...}} unlimited = {static unlimitedDeadline = 9223372036854775807, static unlimitedStartCounter = 9223372036854775807, timeBudget = { budget = -1}, workBudget = {budget = -1}, deadline = 9223372036854775807, counter = 9223372036854589243, static CounterReset = 1000, static UnlimitedTimeBudget = -1, static UnlimitedWorkBudget = -1} finalized = {head_ = 0x7fff6ce4d000, cursorp_ = 0x7fffb9160010} #10 0x00007fffebb19c6d in js::gc::GCRuntime::sweepBackgroundThings (this=this@entry=0x7fffe2a7c968, zones=..., freeBlocks=...) at /build/firefox-esr-KT8g23/firefox-esr-52.2.0esr/js/src/jsgc.cpp:3205 arenas = <optimized out> __for_begin = {mSet = 0x7fffed5f0c4c <BackgroundFinalizePhases+12>, mPos = 9} __for_end = {mSet = 0x7fffed5f0c4c <BackgroundFinalizePhases+12>, mPos = 32} zone = 0x7fff526d4000 phase = <optimized out> emptyArenas = 0x7fff2344b000 fop = {<JSFreeOp> = {runtime_ = 0x0}, freeLaterList = {<js::SystemAllocPolicy> = {<No data fields>}, static kElemIsPod = true, static kMaxInlineBytes = 1024, static kInlineCapacity = 0, static kInlineBytes = 1, mBegin = 0x7fffde7f9d00, mLength = 0, mCapacity = 0, mStorage = {u = {mBytes = "", mDummy = 140736996033024}}, static sMaxInlineStorage = <optimized out>}, jitPoisonRanges = {<js::SystemAllocPolicy> = {<No data fields>}, static kElemIsPod = false, static kMaxInlineBytes = 1024, static kInlineCapacity = 0, static kInlineBytes = 1, mBegin = 0x7fffde7f9d20, mLength = 0, mCapacity = 0, mStorage = {u = { mBytes = " ", mDummy = 32}}, static sMaxInlineStorage = <optimized out>}} lock = {runtime_ = 0x7ffff6c00048, lockGuard_ = {mIsSome = false, mStorage = {u = {mBytes = "\321q\274\367\377\177\000", mDummy = 140737349710289}}}} releaseCount = <optimized out> next = <optimized out> #11 0x00007fffebb19f9f in js::gc::GCRuntime::sweepBackgroundThings (freeBlocks=..., zones=..., this=0x7fffe2a7c968) at /build/firefox-esr-KT8g23/firefox-esr-52.2.0esr/js/src/jsgc.cpp:3405 No locals. #12 js::GCHelperState::doSweep (this=this@entry=0x7fffe2a7f090, lock=...) at /build/firefox-esr-KT8g23/firefox-esr-52.2.0esr/js/src/jsgc.cpp:3405 zones = {static End = <optimized out>, head = 0x7fffdc289000, tail = 0x7fff88118000} freeLifoAlloc = {first = 0x0, latest = 0x0, last = 0x0, markCount = 0, defaultChunkSize_ = 4096, curSize_ = 0, peakSize_ = 21671936, static HUGE_ALLOCATION = 52428800} unlock = {lock = @0x7fffde7f9e30} #13 0x00007fffebb1a093 in js::GCHelperState::work (this=this@entry=0x7fffe2a7f090) at /build/firefox-esr-KT8g23/firefox-esr-52.2.0esr/js/src/jsgc.cpp:3324 logSweeping = {logger = 0x0, payload = {event = 0x7fff00000008, id = TraceLogger_GCSweeping}, isEvent = false, executed = false, prev = 0x7fffe54a0dc0} lock = {runtime_ = 0x7fffe2a7c200, lockGuard_ = {mIsSome = false, mStorage = {u = {mBytes = "\b\360\247\342\377\177\000", mDummy = 140736996044808}}}} logger = <optimized out> #14 0x00007fffebc39214 in js::HelperThread::handleGCHelperWorkload (this=this@entry=0x7fffe2a86360, locked=...) at /build/firefox-esr-KT8g23/firefox-esr-52.2.0esr/js/src/vm/HelperThreads.cpp:1823 unlock = <optimized out> #15 0x00007fffebc45e0e in js::HelperThread::threadLoop (this=0x7fffe2a86360) at /build/firefox-esr-KT8g23/firefox-esr-52.2.0esr/js/src/vm/HelperThreads.cpp:1888 lock = {<js::LockGuard<js::Mutex>> = {lock = @0x7fffe54a0d88}, <No data fields>} stackLimit = 140736924454912 #16 0x00007fffebc33c1a in js::detail::ThreadTrampoline<void (&)(void*), js::HelperThread*>::callMain<0ul> (this=0x7fffe54f7db0) at /build/firefox-esr-KT8g23/firefox-esr-52.2.0esr/js/src/threading/Thread.h:234 No locals. #17 js::detail::ThreadTrampoline<void (&)(void*), js::HelperThread*>::Start (aPack=0x7fffe54f7db0) at /build/firefox-esr-KT8g23/firefox-esr-52.2.0esr/js/src/threading/Thread.h:227 pack = 0x7fffe54f7db0 #18 0x00007ffff7bc3494 in start_thread (arg=0x7fffde7fa700) at pthread_create.c:333 __res = <optimized out> pd = 0x7fffde7fa700 now = <optimized out> unwind_buf = {cancel_jmp_buf = {{jmp_buf = {140736926295808, -1699998519176759858, 0, 140737488340943, 0, 140737354125376, 1700065590481745358, 1699980366686549454}, mask_was_saved = 0}}, priv = {pad = {0x0, 0x0, 0x0, 0x0}, data = {prev = 0x0, cleanup = 0x0, canceltype = 0}}} not_first_call = <optimized out> pagesize_m1 = <optimized out> sp = <optimized out> freesize = <optimized out> __PRETTY_FUNCTION__ = "start_thread" #19 0x00007ffff6e65a8f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:97 No locals.