ARC/async: Returning in a try-block results in wrong codegen

[zedeus]

The type ref int can be any ref type, I discovered it with JsonNode. Returning new(int) or nil instead of nothing triggers the same error. Changing return to discard makes it go away. Returning outside the block also doesn't cause the error.

import asyncdispatch

proc foo*(): Future[ref int] {.async.} =
  try:
    await sleepAsync(100)
  except:
    return

let l = waitFor foo()

... /home/zed/.choosenim/toolchains/nim-#devel/lib/pure/asyncfutures.nim(383, 7) Hint: passing 'fut.error' to a sink parameter introduces an implicit copy; use 'move(fut.error)' to prevent it [Performance]
... /home/zed/.choosenim/toolchains/nim-#devel/lib/pure/asyncmacro.nim(82, 22) Hint: passing ':envP.future5' to a sink parameter introduces an implicit copy; use 'move(:envP.future5)' to prevent it [Performance]
... /home/zed/.choosenim/toolchains/nim-#devel/lib/pure/asyncmacro.nim(272, 31) Hint: passing ':envP.:curExc1' to a sink parameter introduces an implicit copy; use 'move(:envP.:curExc1)' to prevent it [Performance]
... /home/zed/.choosenim/toolchains/nim-#devel/lib/pure/asyncfutures.nim(383, 7) Hint: passing 'fut.error' to a sink parameter introduces an implicit copy; use 'move(fut.error)' to prevent it [Performance]
... /home/zed/src/dev/nim/nitter/src/nitter.nim(9, 5) Hint: 'l' is declared but not used [XDeclaredButNotUsed]
... CC: stdlib_asyncfutures.nim
... CC: nitter.nim
... Error: execution of an external compiler program 'gcc -c  -w   -I'/home/zed/.choosenim/toolchains/nim-#devel/lib' -I/home/zed/src/dev/nim/nitter/src -o /home/zed/.cache/nim/nitter_d/@mnitter.nim.c.o /home/zed/.cache/nim/nitter_d/@mnitter.nim.c' failed with exit code: 1
... /home/zed/.cache/nim/nitter_d/@mnitter.nim.c: In function ‘fooIter__bOHVpAkmxuIVS14H5G65Fg’:
... /home/zed/.cache/nim/nitter_d/@mnitter.nim.c:677:70: error: expected expression before ‘)’ token
...   677 |     eq___ANG79cPfZ9aF0EzkBrohSSEw_2(&(*colonenvP_).colontmpResult2_, );
...       |                                                                      ^

Relevant C code:

complete__aCXgv9alzHqCt9aUCp5bIETg((*(*colonenvP_).colonup_).retFuture1, (*colonenvP_).result4);
(*colonenvP_).colonunrollFinally3_ = NIM_TRUE;
nimln_(156, "/home/zed/.choosenim/toolchains/nim-#devel/lib/pure/asyncfutures.nim");
eqsink___ANG79cPfZ9aF0EzkBrohSSEw(&(*colonenvP_).result6, NIM_NIL);
eq___ANG79cPfZ9aF0EzkBrohSSEw_2(&(*colonenvP_).colontmpResult2_, );
nimln_(69, "/home/zed/.choosenim/toolchains/nim-#devel/lib/system/excpt.nim");
eqsink___rR9boD7urcxl7uyUtE46AOA_2(&(*colonenvP_).coloncurExc1_, NIM_NIL);
(*colonenvP_).colonstate_ = ((NI) 3);