Fatal error: Uncaught TypeError: call_user_func(): Argument #1 ($callback) must be a valid callback, function "is_mixed" not found. about dice HOT 2 OPEN

Okie, I think I have a problem that is very similar to yours. Something like ...

class ToBeInjected {
	function __contruct (ClassToInject $a, string|array|null $b = null) {
		$a ...
		$b ...
		blah blah blah
	}
}

$dice->create("ToBeInjected", [$incoming_b]);

When the class ToBeInjected is created, Dice will exception at Dice.php line 257, Call to undefined method ReflectionUnionType::getName()

If you change $b to be only string or only array or even ?string or ?array it works just fine. Trying to set up a constructParams rule doesn't work either. So I can only conclude that Dice's ability to figure out the arguments does not work for these types of types ...

So new it yourself (instead of $dice->create()), or change your params to be more precise...

Just FYI, in my use case, it makes sense because the input is EITHER a string, or an array, and for each case we handle things slightly differently. Having the input to be string|array makes sure (forces) that we have only one input, and not end up a situation where we were given both a string and an array and have to choose between one or the other.

PS. PHP 8.1, Dice 4.0.4

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Sorry, just wanted to add on another case for FYI:

class ToBeInjected {
	function __contruct (ClassInject $a, ?array $b = null, ?string $c = null) {
		$a ...
		$b ...
		$c ...
		blah blah blah
	}
}

$dice->create("ToBeInjected", [null, $incoming_c]);

This does NOT work. You need to do:

$dice->create("ToBeInjected", [array(), $incoming_c]);

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