I've introduced a new CompileError type, from which ParseError
inherits. These errors are not parse errors in the narrow sense
of the term, even though they happen to be generated during
parsing in our implementation. Additionally reusing the ParseError
class for this purpose would change existing error messages (if
the exception is not caught) from a "Fatal error:" to a "Parse
error:" prefix, and also the error kind from E_COMPILE_ERROR to
E_PARSE.