SourceKitten crashes when a documentation comment ends with an extended grapheme cluster.

[Lukas-Stuehrk]

NSString and Swift's String handle extended grapheme clusters differently. While removing trailing whitespace, SourceKitten tries to create a UnicodeScalar from an NSString character which does not necessarily succeed. Because of that SourceKitten crashes at force-unwrapping the unicode scalar (String+SourceKitten.swift, line 241 in trimmingTrailingCharacters(in characterSet: CharacterSet).

Minimal example:

/**💣*/
class Foobar{
}