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In a custom Drupal 8 module I decided to wrap a line of code in a try...catch block, in case $node was null.

I understand that in php errors and exceptions are different, and according to Error message - Trying to get property of non-object this is an error, so will not be handled by try...catch, and the code should continue to run after the error.

However when this code runs under Drupal 8 the error hander raises an exception. So I added the try...catch block. But the exception is still unhandled crashed the program.

This is a cut-down version of my code:

$node = null;
try {
  // The next line results in an unhandled exception 
  $f = $node->field_example;
} catch (Exception $e) {
  // Never gets here
  watchdog_exception('example', $e);
}
// Never gets here

Am I missing something? Surely this can't be the intended behaviour?

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  • 3
    Yes, that’s the behaviour PHP intends; it has exceptions and errors as you say, and fundamentally misusing a data type is an example of an error. To avoid, use instanceof, is_object or similar
    – Clive
    May 23 '20 at 17:55
  • 2
    It's explained in Errors in PHP 7. As the Error hierarchy does not inherit from Exception, code that uses catch (Exception $e) { ... } blocks to handle uncaught exceptions in PHP 5 will find that these Errors are not caught by these blocks. Either a catch (Error $e) { ... } block or a set_exception_handler() handler is required.
    – apaderno
    May 23 '20 at 18:36
  • 5
    You can also just catch (\Throwable $e) if you want both
    – Clive
    May 23 '20 at 19:16
  • Thanks @Clive that works.
    – hughworm
    May 24 '20 at 9:46
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I actually over-simplified by question. The crash doesn't happen in the simple case I posted, just an error and execution continues. It arises when I use field API syntax to refer to a null referenced entity, and only then when the target_id is not null.

$node->field_foo->target_id = 999; // term 999 does not exist
try {
  // The next line results in an unhandled exception 
  $v = $node->field_foo->entity->field_bar->value;
} catch (\Exception $e) {
  // Never gets here
  watchdog_exception('example', $e);
}
// And never gets to continue here

The issue was why and Drupal does this. The solution (thanks @Clive) is to replace catch (\Exception $e) with catch (\Throwable $e)

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You are trying to catch Exception, when you should be catching \Exception.

} catch (\Exception $e) {

EDIT: Assuming that an exception is actually thrown as stated in the original post.

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