Make Monolog respond to PHP Errors

## Make Monolog respond to PHP Errors

### Acceptance Criteria
1. PHP errors are logged.

### Tasks
- Implement [Monolog ErrorHandler utility class](https://github.com/Seldaek/monolog/blob/master/src/Monolog/ErrorHandler.php).

### Additional Notes
- This change is necessary because modern browsers do not display response content of cross-origin requests if there is an error.