external command 'git' exited with code 1

Stream: mathlib4

[Violeta Hernández]

I suddenly started getting this error and now lean build doesn't work, what's going on?
image.png

[Julian Berman]

lake build --help doesn't seem to document its options (that seems like a bug worth filing though my vague recollection is I think I have noticed this before and maybe found an existing one).
But just guessing that lake build --verbose would do something, it appears to -- does doing that tell you at least what git command was run (and maybe even its output)?

[Julian Berman]

(Ah, --verbose is an option lake itself is happy with, and is documented in lake --help, maybe this is what I recall noticing previously.)

[Violeta Hernández]

image.png
This is the output of verbose

[Violeta Hernández]

Well... I found a random package-lock.json.trace file, deleted it, and things seem to be normal again...

[Kevin Buzzard]

This can happen if a build is cancelled midway through I guess.

[Julian Berman]

I just encountered this exact error condition myself when switching between branches...

~/Development/Mathlib4 is a git repository on bhargava-factorial
⊙  lake build --verbose                                                                                                                                                                                                                                                                                 julian@Mini
trace: ././.lake/packages/proofwidgets> git fetch --tags --force origin
info: proofwidgets: checking out revision '07f60e90998dfd6592688a14cd67bd4e384b77b2'
trace: ././.lake/packages/proofwidgets> git checkout --detach 07f60e90998dfd6592688a14cd67bd4e384b77b2 --
trace: stderr:
error: Your local changes to the following files would be overwritten by checkout:
    widget/package-lock.json.trace
Please commit your changes or stash them before you switch branches.
Aborting
error: external command 'git' exited with code 1

[Julian Berman]

(I don't think anything is to be done? Kevin's probably right, the other branch I was on started building mathlib and I probably killed it by exiting neovim. Just noting in case yet more people run into this.)