Description:
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I need to have keys returned in an array_slice() operation where I remove some n first elements and keep the rest.  That means that the third parameter must be NULL and the fourth is TRUE. 

The third parameter is defined to be of type int, with a default of NULL.  I get non-fatal error messages when specifying a NULL parameter value to override the default for the fourth parameter. 

Test script:
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$arr = ['a' => 45, 'b' => 30];
$exp = array_slice($exp, 1, null, true);

Expected result:
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$exp = ['b' => 30] and no debug error message returned.

Actual result:
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$exp = ['b' => 30] and error message returned.
Severity	Code	Description	Project	File	Line	Suppression State
Warning	PHP0406	Argument '3' passed to array_slice() is expected to be of type int, null given	...