[pavog]

ChunkLoadExceptionProblem searched the stack trace below "Encountered an unexpected exception" with (\n.*)*at.*.
The nested quantifiers backtrack per character, so on entries of about 1 MB the patterns hit the backtrack or JIT stack limit and the problem was silently not detected.

This PR skips whole lines possessively with (?:.*+\n)*?, so there is one backtracking point per line instead of per character.
The cause line is matched from its start: a stack trace line (\h*at followed by the package) or the exception chain before "Exception generating new chunk".
Without that, .*at.* still backtracked within every line, which failed without PCRE JIT.

The fragments are constants with examples, because they are used in three patterns.

Changes

• add UNEXPECTED_EXCEPTION and STACK_TRACE_PACKAGE to ChunkLoadExceptionProblem
• rewrite the three stack trace patterns with them
• remove ChunkLoadExceptionProblem from KNOWN_UNSAFE_PATTERNS