Framework: Fix all phpstan level 5 issues

system/src/Grav/Framework/Flex/FlexCollection.php

@@ -9,6 +9,7 @@
 
 namespace Grav\Framework\Flex;
 
+use Doctrine\Common\Collections\Collection;
 use Doctrine\Common\Collections\Criteria;
 use Grav\Common\Debugger;
 use Grav\Common\Grav;
@@ -125,7 +126,7 @@ class FlexCollection extends ObjectCollection implements FlexCollectionInterface
 
     /**
      * @param array $filters
-     * @return FlexCollectionInterface
+     * @return FlexCollectionInterface|Collection
      */
     public function filterBy(array $filters)
     {

system/src/Grav/Framework/Flex/FlexForm.php

@@ -82,7 +82,7 @@ class FlexForm implements FlexFormInterface
     }
 
     /**
-     * @return Data|FlexObjectInterface
+     * @return Data|FlexObjectInterface|object
      */
     public function getData()
     {
@@ -103,7 +103,7 @@ class FlexForm implements FlexFormInterface
         $value = $this->data ? $this->data[$name] : null;
 
         // Return the form data or fall back to the object property.
-        return $value ?? $this->getObject()->value($name);
+        return $value ?? $this->getObject()->getFormValue($name);
     }
 
     public function getDefaultValue(string $name)

system/src/Grav/Framework/Flex/FlexObject.php

@@ -736,7 +736,7 @@ class FlexObject implements FlexObjectInterface, FlexAuthorizeInterface
         }
 
         $grav = Grav::instance();
-        /** @var Flex $flex */
+        /** @var Flex|null $flex */
         $flex = $grav['flex_objects'] ?? null;
         $directory = $flex ? $flex->getDirectory($type) : null;
         if (!$directory) {

system/src/Grav/Framework/Interfaces/RenderInterface.php

@@ -29,7 +29,7 @@ interface RenderInterface
      * @example {% render object layout 'custom' with { variable: 'value' } %}
      *
      * @param string|null $layout  Layout to be used.
-     * @param array|null  $context Extra context given to the renderer.
+     * @param array       $context Extra context given to the renderer.
      *
      * @return ContentBlockInterface|HtmlBlock Returns `HtmlBlock` containing the rendered output.
      * @api