Out of bounds error when use seq with emscripten

[snjax]

Here is the code
    
    
    import macros
    import random
    
    macro EMSCRIPTEN_KEEPALIVE*(someProc: untyped): typed =
      result = someProc
      result.addPragma(newIdentNode("exportc"))
      when defined(cpp):
        result.addPragma(newNimNode(nnkExprColonExpr).add(
          newIdentNode("codegenDecl"),
          newLit("__attribute__((used)) extern \"C\" $# $#$#")))
      else:
        result.addPragma(newNimNode(nnkExprColonExpr).add(
          newIdentNode("codegenDecl"),
          newLit("__attribute__((used)) $# $#$#")))
    
    proc test: int32 =
      var a:seq[int] = @[1, 2, 3]
      a.add(1)
      return int32(a.len)
    
    proc fromNimFunction: int32{.EMSCRIPTEN_KEEPALIVE.} =
      return test()
    
    
    
    Run

Got 
    
    
    RuntimeError: memory access out of bounds
    
    
    Run

My nim.cfg 
    
    
    @if wasm:
      d:emscripten
    @end
    
    @if emscripten or wasm:
      cc = clang
      clang.exe = "emcc"
      clang.linkerexe = "emcc"
      clang.options.linker = ""
      cpu = "i386"
      @if wasm:
        passC = "-s WASM=1 -s 'BINARYEN_METHOD=\"native-wasm\"' -Iemscripten -s 
SINGLE_FILE=1 "
        passL = "-s WASM=1 -s 'BINARYEN_METHOD=\"native-wasm\"' -Lemscripten -s 
SINGLE_FILE=1 -s ALLOW_MEMORY_GROWTH=1 "
      @end
      
      @if release:
        passC %= "-O3 -flto -ffast-math"
        passL %= "-O3 -flto -ffast-math"
      @end
      
      #Fix _setjmp/longjmp problem. 
https://irclogs.nim-lang.org/24-09-2017.html#12:19:50
      d:nimStdSetjmp              # 
https://irclogs.nim-lang.org/24-09-2017.html#20:13:18
    
    @end
    
    
    Run