Reading zero or negative byte with asyncfile leads to different behavior in linux and windows

[ringabout]

Related: #15148

echo "123" >> test.txt

block:
  proc saveEmpty() {.async.} =
    let
      file = open_async("test.txt", fmRead)
    discard await file.read(0)
    file.close()

  waitFor saveEmpty()

Current Output

in linux

Exception message: index out of bounds, the container is empty
Exception type: [IndexError]

in windows

Error: unhandled exception: D:\QQPCmgr\Desktop\Nim\lib\pure\asyncfile.nim(219, 20) `bytesCount > 0`  [AssertionDefect]
Error: execution of an external program failed: 'D:\QQPCmgr\Desktop\Nim\test.exe '

Expected

compile or raise assert error

[Araq]

Neither the assertion nor the IndexError are supposed to be caught anyway so I don't see a problem here. You shall not continue to run your program after a detected bug.

[konsumlamm]

Neither the assertion nor the IndexError are supposed to be caught anyway so I don't see a problem here. You shall not continue to run your program after a detected bug.

Wouldn't it be better to get an assertion failure that works the same on all platform than to get some internal error? I don't think anyone wants to catch the exception.

[ringabout]

Exception message: index out of bounds, the container is empty Exception type: [IndexError]

Doesn't this mean there is a bug in stdlib? I forgot to say "test.txt" is not empty.

Full error messages:

/root/prologue/hello.nim(10) hello
/root/.choosenim/toolchains/nim-#devel/lib/pure/asyncmacro.nim(262) saveEmpty
/root/.choosenim/toolchains/nim-#devel/lib/pure/asyncmacro.nim(29) saveEmptyNimAsyncContinue
/root/prologue/hello.nim(7) saveEmptyIter
/root/.choosenim/toolchains/nim-#devel/lib/pure/asyncfile.nim(292) read
/root/.choosenim/toolchains/nim-#devel/lib/pure/asyncfile.nim(276) cb
/root/.choosenim/toolchains/nim-#devel/lib/system/fatal.nim(53) sysFatal
[[reraised from:
/root/prologue/hello.nim(10) hello
/root/.choosenim/toolchains/nim-#devel/lib/pure/asyncdispatch.nim(1937) waitFor
/root/.choosenim/toolchains/nim-#devel/lib/pure/asyncfutures.nim(375) read
]]
Error: unhandled exception: index out of bounds, the container is empty
Async traceback:
  /root/prologue/hello.nim(10)                                        hello
  /root/.choosenim/toolchains/nim-#devel/lib/pure/asyncmacro.nim(262) saveEmpty
  /root/.choosenim/toolchains/nim-#devel/lib/pure/asyncmacro.nim(29)  saveEmptyNimAsyncContinue
  /root/prologue/hello.nim(7)                                         saveEmptyIter
  /root/.choosenim/toolchains/nim-#devel/lib/pure/asyncfile.nim(292)  read
  /root/.choosenim/toolchains/nim-#devel/lib/pure/asyncfile.nim(276)  cb
  /root/.choosenim/toolchains/nim-#devel/lib/system/fatal.nim(53)     sysFatal
Exception message: index out of bounds, the container is empty
Exception type: [IndexDefect]