Rule index read from compiled bytecode is used to index rules_table without a bounds check:
- OP_PUSH_RULE dereferences rules_table[r1.i] and indexes rule_matches_flags with the same value, unchecked
- OP_INIT_RULE only had an assert, which is a no-op under NDEBUG
- OP_MATCH_RULE right below them already guards the index with ensure_within_rules_arena
Added the same YR_PARANOID_EXEC guard to both. A crafted .yrc with an out-of-range rule index reaches this through yr_rules_scan_mem and reads past the table; test-exec covers it.