Description:
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The "Cannot use positional argument after named argument" exception is sometimes thrown in situations where named parameters isn't supported.

Test script:
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<?php
$null = null;

// https://3v4l.org/qgfV2
assert(assertion: is_null($null));

// https://3v4l.org/q8Oqq
$a = is_null($null);
assert(assertion: $a);

Expected result:
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Either named parameters being supported (= no error).
Or named parameters not being supported and the code resulting in a parse error.

NOT an error referring to named arguments, while the language construct doesn't seem to support it.

Actual result:
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Fatal error: Cannot use positional argument after named argument in /in/qgfV2 on line 3