TypeError: array_values(): Argument #1 ($array) must be of type array, null given

I was able to quickfix this using a fallback empty array, if null:

$this->value = array_values($active_facet_values ?? []);

Any ideas about the root cause? Is this an appropriate fix?

Hmm, interesting.
You would need to debug this in getActiveFacetValues() in modules/facets_exposed_filters/src/Plugin/views/filter/FacetsFilter.php

I wonder why this function returns NULL in your case.

I experienced the same issue and the issue fork resolved it for me.

While I dont mind committing the above, I'd rather find out why this value is null.
Anyone having this issue who could debug?

I can't reproduce this myself.

Does this happen on existing views + facets exposed filters only? Or also on newly created views + facets exposed filters?

@strykaizer:

getActiveFacetValues() in my case always directy returns []
from these lines:

if (!isset($_GET[$this->options["expose"]["identifier"]])) {
  return [];
}

aaaaaaaaah I found it!!

It's a logical mistake in code:

  if($processed_facet) {
      $facet = $processed_facet;
    } else {
      /** @var \Drupal\facets\FacetInterface $facet */
      $facet = $this->getFacet();

      $results = [];
      $active_facet_values = $this->getActiveFacetValues();  // <<<<<<<<<< $active_facet_values is only defined here!
      [...]
  }

but

$this->value = array_values($active_facet_values);

is called AFTER the if / else, so $active_facet_values can be undefined!

Which PHP Version are you using @strykaizer? I guess an older one?

@strykaizer I created a further branch to fix this, but I'm unsure about one of the following fixed to correct this:
1. Move $this->value = array_values($active_facet_values); into the else
2. Move $active_facet_values = $this->getActiveFacetValues(); before the if / else
3. Define $active_facet_values = []; before the if/else

Ic, I assume you are placing your "exposed filters" in a block in that case?
Thanks for debugging, I'll fix this asap!

@strykaizer right!

Thanks @anybody

Automatically closed - issue fixed for 2 weeks with no activity.