[heft] stuck in Cancelling incremental build... phase

[UberMouse]

Summary

I'm running into issues with watch builds in Heft. Launch heft into a watch mode session, edit a typescript file, maybe it works the first time, usually not, but it never works for any edits after that. As soon as the file change is picked up by the typescript phase I just have it log

New run requested by typescript
Cancelling incremental build...

and then it locks up and nothing further happens.

Repro steps

heft start this is an alias for heft package-watch --serve
our phases are setup with a build phase that uses the typescript plugin, and a package phase which uses the rspack plugin (which I have copied into our repo since it isn't published yet)

edit a typescript file

Expected result: typescript watch phase rebuilds, package phase rebuilds

Actual result: typescript watch phase triggers, nothing happens

Details

Not sure if there is any further debug information I can pull out to help with this? Running heft with --debug doesn't log any extra information when the typescript phase requests a new run

Standard questions

Please answer these questions to help us investigate your issue more quickly:

Question	Answer
@rushstack/heft version?	0.75.0
Operating system?	NixOS
Node.js version (node -v)?	22.14.0

[octogonz-dev]

@dmichon-msft @iclanton could this be a recent regression from the new watch features?

[dmichon-msft]

On investigation, this is a bug in heft-rspack-plugin not handling the scenario, but still digging more into exactly where it is breaking.

[dmichon-msft]

Looks like @rushstack/heft-rspack-plugin will hang if you trigger a watch-mode rebuild that doesn't modify any of the files processed by rspack. @bmiddha is working on a fix.

[UberMouse]

Nice. Unrelated to this, but one issue I found with the rspack plugin is that this module not found check in the configuration loader masks errors loading the config, they seem to bubble up as the same module not found error, but the config file exists. Things like, at least, importing a dependency that doesn't exist, but I think also code errors evaluating the config file.

[bmiddha]

@UberMouse would you mind filing a separate issue for ERR_MODULE_NOT_FOUND? This is something that we can also look into for heft-webpack5-plugin.

[UberMouse]

Done @bmiddha #5459