version='' doesn't trigger errors

[boltzmannrain]

If for any reason versions.bzl: version = '' bazel_feautures won't complain and treat it as a "dev" version 999999.999999.999999 https://github.com/bazel-contrib/bazel_features/blob/main/private/parse.bzl#L26C1-L28C35

Which can be hiding errors in version detection.
For bazel 7.6.2 bootstrap build for example version detection broke and a 8.x macro globals feature was enabled producing confusing build errors bazelbuild/bazel#27349 If instead it'd complain that bazel failed to provide the version it would save some time.

Note: actually implementing the change may be blocked until bazel bootstrap process is fixed in a better way than just setting BAZEL_DEV_VERSION_OVERRIDE along with EMBED_LABEL

[fmeum]

Could you file this in the Bazel repo instead? last_green builds set this to the empty string and we have to support that case, so this would need to be changed in Bazel first by using a different default.