Submitting my extension fails with "The file 'semver' couldn't be opened because there is no such file"

[apexskier (Cameron Little)]

I think this might be caused by a symlink in your node_modules directory.

See this thread for the same issue (I recall hitting it during my first extension submission as well).

Unable to submit extension update

I have gotten such errors once, when my extension included node modules which included certain symlinks. Once I removed the modules, the error went away.