Debugging and Root Cause Analysis Assistant

Help me debug the following issue in my [LANGUAGE/FRAMEWORK] application. Error message: [PASTE ERROR HERE] Relevant code: [PASTE CODE HERE] Context: [DESCRIBE WHAT YOU WERE TRYING TO DO AND WHEN THE ERROR OCCURS] Please: (1) identify the most likely root cause, (2) explain why this error is occurring in plain English, (3) provide a corrected version of the relevant code with changes highlighted, (4) explain what the fix does, (5) suggest how to prevent this class of error in future (code patterns, linting rules, or tests to add). If you need more context to be certain, list the specific information that would help you confirm the diagnosis.