Issue #3207373: Hide block if facets are empty.

Closes #3207373

src/Plugin/Block/FacetsBlock.php

@@ -279,11 +279,16 @@ class FacetsBlock extends BlockBase implements ContainerFactoryPluginInterface {
     // Allow other modules to alter the facets array.
     $this->moduleHandler->alter('facets_block_facets', $facets);
 
-    return [
-      '#theme' => 'facets_block',
-      '#show_title' => $show_title,
-      '#facets' => $facets,
-    ];
+    if (!empty($facets)) {
+      return [
+        '#theme' => 'facets_block',
+        '#show_title' => $show_title,
+        '#facets' => $facets,
+      ];
+    }
+    else {
+      return [];
+    }
   }
 
 }