Program termination

if $problem { exit $error-code }

An exit runs all appropriate scope-leaving blocks such as LEAVE, KEEP, or UNDO, followed by all END blocks, followed by all destructors that do more than just reclaim memory, and so cannot be skipped because they may have side effects visible outside the process. If run from an embedded interpreter, all memory must also be reclaimed. (Raku does not yet have a thread-termination policy, but will need to before we're done.)