This guide helps you understand common error messages and how to collect useful diagnostics.

Common error classes

  • Parse errors: syntax/indentation problems detected before execution.
  • Name/lookup errors: missing variables, functions, or modules.
  • Runtime errors: type mismatches, out-of-range access, invalid operations.

Enabling diagnostics

  • Build with -DFUN_DEBUG=ON to enable additional assertions and debug messages (see build.md).
  • Run with smaller, focused scripts to isolate issues.

Getting useful reports

  • Capture the minimal script that reproduces the issue.
  • Note your build options and platform.
  • Record the full error output from the CLI (fun), including line/column if present.

Tips

  • Use prints or logging sparingly to narrow down failing code.
  • Start from a passing simple case and add complexity until it breaks.

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