Print a value
debug.log("Health:", health)
Print the value just before the code that fails. Check lookup results before reading object properties.
Start with the first error
Output can report a script path, line, and function. Open that location and fix the first failure before interpreting later messages. An invalid handle often means the object was removed. A missing key may mean a UI display name was used instead of its Script key.
Run checks
Use the Test API for in-game checks. See Script errors for common fixes.