In scala.util.parsing.combinator.lexical.StdLexical handling of unclosed multi-line comments (/* ... */) does not seem to work as expected.

If an unclosed multi-line comment is encountered, instead of returning one ErrorToken(unclosed comment), two ErrorToken(illegal character) tokens are returned (one for / and another for *) and scanning continues.

The issue is described in this comment.
#397 (comment)

@JakobLyngPetersen and I are working on a fix.