from @keith:

i saw this case today which appeared to happen because 1 version wrote the lockfile then a newer version read it:

ERROR: Error computing the main repository mapping: Failed to read and parse the MODULE.bazel.lock file with error: Null envVariables. Try deleting it and rerun the build.

We should properly deal with new fields being added to the lockfile mechanism (treat them as empty) and not just throw everything out the window. Especially, asking the user to delete the lockfile should be a last resort.