I need the errors that are crashing both my Python scripts and Java classes traced, fixed, and verified. The issues show up during runtime, so I will provide the source files together with the current stack traces and any relevant logs. Your job is to: • locate the exact fault in each language • apply clean, well-commented fixes without altering unrelated logic • run the programs with representative data to confirm stability • send back the corrected files plus a concise changelog that explains what you did and why I have firm time limits on this task, so please be ready to start right away and keep me updated with quick checkpoints until everything runs smoothly.