0.52 is in unstable now, Current status on master-0.56 branch,
tsc src/Graph.ts:92:31 - error TS1345: An expression of type 'void' cannot be tested for truthiness 92 if (plugin.options) return plugin.options(acc) || acc; ~~~~~~~~~~~~~~~~~~~ src/ast/ExecutionPathOptions.ts:1:23 - error TS7016: Could not find a declaration file for module 'immutable'. '/usr/share/nodejs/immutable/dist/immutable.js' implicitly has an 'any' type. Try `npm install @types/immutable` if it exists or add a new declaration (.d.ts) file containing `declare module 'immutable';` 1 import Immutable from 'immutable'; ~~~~~~~~~~~ src/utils/callIfFunction.ts:2:39 - error TS2349: This expression is not callable. Not all constituents of type '(() => T) | (T & Function)' are callable. Type 'T & Function' has no call signatures. 2 return typeof thing === 'function' ? thing() : thing; ~~~~~ src/utils/collapseSourcemaps.ts:96:7 - error TS2322: Type 'number' is not assignable to type 'undefined'. 96 segment[4] = nameIndex; ~~~~~~~~~~ src/utils/collapseSourcemaps.ts:96:15 - error TS2493: Tuple type '[number, number, number, number]' of length '4' has no element at index '4'. 96 segment[4] = nameIndex; ~ src/watch/index.ts:216:5 - error TS2322: Type 'Set<unknown>' is not assignable to type 'Set<string>'. Type 'unknown' is not assignable to type 'string'. 216 this.watched = watched; ~~~~~~~~~~~~ Found 12 errors. Files: 277 Lines: 120117 Nodes: 418097 Identifiers: 159915 Symbols: 104609 Types: 9282 Memory used: 169166K I/O read: 0.09s I/O write: 0.00s Parse time: 1.76s Bind time: 0.85s Check time: 1.75s Emit time: 0.00s Total time: 4.36s node-immutable includes type definitions, but it seems to be not enough. It has 'declare module Immutable' though this build is expecting it to be 'declare module immutable' (i in small as opposed to I in caps).