I'm running the maintenance script convertExtensionToRegistration.php in an environment with debugging and warnings turned on. When run, i get this warning message:
Warning: array_key_exists(): The first argument should be either a string or an integer in /maintenance/convertExtensionToRegistration.php on line 101
Next time i run into it, I'll send you a copy. Interestingly, i've had it not happen on a few that i've run. Perhaps it's a coding issue on my side?
Maybe, I can't really say without looking at the file. The script attempts to handle all cases, but the whole concept is a bit hacky so it doesn't really handle edge cases gracefully.
Please re-open if you can reproduce this and provide the file that was being converted.