Description
When the IDE starts up it appears to scan the library.properties files of each of the libraries under the users sketchbook directory.
If it encounters a version number that it doesn't like, it prints an error to stderr and exits.
Unfortunately, at least on linux, stderr messages are not seen when the user starts the IDE by clicking on the arduino startup script.
It seems inappropriate for the IDE to abort just because a library may have a version number that it does not like. In my view it could (should) ignore these strict rules (yeah, yeah, that would be against the semver spec); however, when there is not an update check or there is no way of doing an update, the contents of the version string are pretty irrelevant, so there is no need to be so strict.
At a minimum if the strict naming convention is to be enforced and the IDE is going to abort, it should at least put a dialog so that users can figure out what the problem is and then either abort or ignore that library.
However, My preference would be to relax the checking and use the version string "as is" whenever possible, which is probably most of the time.