Issue #3416266 by grimreaper, kevinquillen, hydra: Switch from useing array_pop/array_push for section manipulation to preserve key integrity and ensure module integration compatibility

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Closes #3416266

src/SectionLibraryRender.php

@@ -81,8 +81,10 @@ class SectionLibraryRender implements TrustedCallbackInterface {
         // Add save to library link to the built section.
         elseif (isset($section['configure']) && isset($section['configure']['#url'])) {
           $params = $section['configure']['#url']->getRouteParameters();
-          // Pop the last item to add the link before it.
-          $last_item_section = array_pop($sections[$key]);
+          // Save the layout to replace it later in the last position.
+          $layout_section = $sections[$key]['layout-builder__section'];
+          unset($sections[$key]['layout-builder__section']);
+
           $add_to_library_url = Url::fromRoute(
             'section_library.add_section_to_library',
             [
@@ -108,8 +110,9 @@ class SectionLibraryRender implements TrustedCallbackInterface {
             '#url' => $add_to_library_url,
             '#access' => $add_to_library_url->access(),
           ];
-          // Push the last item again.
-          array_push($sections[$key], $last_item_section);
+
+          // Ensure layout section is the last item.
+          $sections[$key]['layout-builder__section'] = $layout_section;
         }
       }