FormElements: Fix return type of createElement() method and related…

… code

This fixes the confusion of phpstan. Since the `createElement()` element returns an instance
of `FormElement`, phpstan cannot find an `addHtml()` method for it, for example.
The return type must therefore be `FormElement & BaseHtmlElement`.

src/FormElement/FormElements.php

@@ -3,6 +3,7 @@
 namespace ipl\Html\FormElement;
 
 use InvalidArgumentException;
+use ipl\Html\BaseHtmlElement;
 use ipl\Html\Contract\FormElement;
 use ipl\Html\Contract\FormElementDecorator;
 use ipl\Html\Contract\ValueCandidates;
@@ -29,7 +30,7 @@ trait FormElements
     /** @var bool Whether the default element loader has been registered */
     protected $defaultElementLoaderRegistered = false;
 
-    /** @var FormElement[] */
+    /** @var (FormElement & BaseHtmlElement)[] */
     private $elements = [];
 
     /** @var array<string, array<int, mixed>> */
@@ -38,7 +39,7 @@ trait FormElements
     /**
      * Get all elements
      *
-     * @return FormElement[]
+     * @return (FormElement & BaseHtmlElement)[]
      */
     public function getElements()
     {
@@ -70,7 +71,7 @@ public function hasElement($element)
      *
      * @param string $name
      *
-     * @return FormElement
+     * @return FormElement & BaseHtmlElement
      *
      * @throws InvalidArgumentException If no element with the given name exists
      */
@@ -137,7 +138,7 @@ public function addElement($typeOrElement, $name = null, $options = null)
      * @param string $name    Name of the element
      * @param mixed  $options Element options as key-value pairs
      *
-     * @return FormElement
+     * @return FormElement & BaseHtmlElement
      *
      * @throws InvalidArgumentException If the type of the element is unknown
      */
@@ -154,7 +155,7 @@ public function createElement($type, $name, $options = null)
             ));
         }
 
-        /** @var FormElement $element */
+        /** @var FormElement & BaseFormElement $element */
         $element = new $class($name);
 
         if ($options !== null) {