Description:
------------
array_merge() function returns NULL if any of the arguments are not arrays.
This makes for a lot of boilerplate code / guard clauses, such that I, more often than not, rather end up using foreach for merging instead.

I don't know if I am the only one who expects it to either:

- return a merged array containing all of the valid arrays' keys/values, or
- return a merged array containing all of the valid arrays' keys/values before the first "invalid" argument.

This latter might (or might not) be preferrable on performance considerations.

Please propose a change and/or vote on proposal if this is even possible.
If so, I may make a patch if needed.

EDIT: as this seems similar to #64909, another proposal would be the ability to change the emitted E_WARNING into a catchable fatal error.

This is quite strange that in such case we could catch a java.lang.NullPointerException in Java, but nothing in PHP; quite counter-productive.


Test script:
---------------
<?php
var_dump(array_merge(['what', 'ever'], false));

Expected result:
----------------
array(2) {
  [0]=>
  string(4) "what"
  [1]=>
  string(4) "ever"
}

Actual result:
--------------
<br />
<b>Warning</b>:  array_merge(): Argument #2 is not an array in <b>[...][...]</b> on line <b>2</b><br />
NULL