fix(version): do not cache a comparator that failed to build

[arpitjain099]

getComparator caches the constructed comparator in v.comparators[format] unconditionally, including when construction returned an error:

comparator, err = newSemanticVersion(v.Raw, false) // may return a broken comparator + err
...
v.comparators[format] = comparator
return comparator, err

On a parse failure the constructor returns a zero-value comparator (for Semantic/JVM/Bitnami its internal *hashiVer.Version is nil) together with an error. Caching it means the next lookup for that format hits the cache and returns it with a nil error, so the caller proceeds to Compare, which dereferences the nil version and panics. For formats without a pointer it silently compares against an empty version, i.e. a false negative in matching.

The map persists across calls once a pointer-receiver entry point (Is / Validate) populates it, so a repeated comparison on the same *Version triggers it. In-tree this is reachable from matcher/rpm/rhel_eus.go neededFixes, which calls v.Is(LT, ...) in a loop on the same package version.

Repro:

v := New("3.e", SemanticFormat)
other := New("1.0", SemanticFormat)
v.Is(LT, other) // caches the broken comparator; error is logged/handled
v.Is(LT, other) // cache hit: nil error, then panic in Compare

The fix returns early on a build error so the broken comparator is never cached, and the error surfaces consistently instead. Added a regression test. go test ./grype/version/ passes.