Handling `sysFatal` gracefully

[adigitoleo]

Unhandled sysFatal from top level scope can crash the repl:

%zsh> inim
👑 INim 0.6.1
Nim Compiler Version 1.6.0 [Linux: amd64] at /usr/bin/nim
nim> var s = newSeq[int](5)
nim> s[5] = 42
fatal.nim(53)            sysFatal
Error: unhandled exception: value out of range: -1 notin 0 .. 9223372036854775807 [RangeDefect]

Other unhandled sysFatal don't show the error message:

%zsh> inim
👑 INim 0.6.1
Nim Compiler Version 1.6.0 [Linux: amd64] at /usr/bin/nim
nim> proc oof() =
....   var s = newSeq[int](5)
....   s[5] = 42
....
nim> oof()
/usr/lib/nim/lib/system/fatal.nim(53) sysFatal

[0atman]

confirmed, these should not crash the repl, ideally. Perhaps they should be removed from execution so that further commands can continue?

[adigitoleo]

Looks like the crash isn't happening any more with nim 1.6.6, the message is still missing in the second case however.

[adigitoleo]

Crash is back, either I was talking nonsense before or it is reintroduced. My naive idea for this was to somehow catch sysFatal during the internal compile cycle (although I understand that it's more like a panic than an exception), but that requires a better understanding of fatal.nim than I have:
https://github.com/nim-lang/Nim/blob/devel/lib/system/fatal.nim

In particular, Nim is not always simply raiseing something, there's a few platform/compiler-flag specific behaviours.

[adigitoleo]

On INim v1 with nim v2.0.8 (linux amd64) neither of these are crashing anymore. The first case no longer throws sysFatal. The second does, but it is not crashing the REPL anymore. If you can confirm that there is no crash on Windows either then this can probably be closed.