Errors & exit codes

Stage	Exit code	Example
Lexer error	65	Unterminated string, unexpected character, inconsistent indentation
Parse error	65	Missing be/to, malformed block, unexpected token
Runtime error	70	Undefined variable, type mismatch, division by zero, wrong arity

All errors are reported with the offending line number and a plain-English message — there is deliberately no stack trace to parse.