PHP - Rewrite For Custom Url

I'm sure it's not much, but I'm not understanding something with custom error handlers:

I've created a custom error handler, which I initially set when my page loads :

set_error_handler(array ( new ErrorHandler(), 'handleError' ));

It seems to catch all internal PHP errors, such as if I: var_dump($non_existing_var); right after the set_error_handler....

Now, I have an object that throws an exception after:

set_error_handler(array ( new ErrorHandler(), 'handleError' )); 
$locale = new \CorbeauPerdu\i18n\Locale(...); // this should throw an exception 
...

I thought that with an error handler set, I could 'skip' the try/catch for it, but doing so, PHP spits out in its internal log:

PHP Fatal error: Uncaught CorbeauPerdu\i18n\LocaleException: ....

My error handler doesn't catch it at all before, thus my page breaks!!

If I want it to go through the error handler, I have to init my Locale with a try/catch and use trigger_error() like so:

set_error_handler(array ( new ErrorHandler(), 'handleError' ));

try { 
  $locale = new \CorbeauPerdu\i18n\Locale(...); // this should throw an exception 
}
catch(Exception $e) { 
  trigger_error($e->getMessage(), E_USER_ERROR); 
} 
...

Is this normal ? I thought one of the goals of the error_handler was to catch anything that wasn't dealt with?

Thanks for your answers!

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