Issue #3426535 by yas: Fix an error: 'TypeError: Unsupported operand types:...

Issue #3426535 by yas: Fix an error: 'TypeError: Unsupported operand types: null + array in Drupal\k8s\Plugin\cloud\launch_template\K8sCloudLaunchTemplatePlugin->buildLaunchForm()

Closes #3426535

modules/cloud_service_providers/k8s/src/Plugin/cloud/launch_template/K8sCloudLaunchTemplatePlugin.php

@@ -529,8 +529,8 @@ class K8sCloudLaunchTemplatePlugin extends CloudPluginBase implements CloudLaunc
           ->get('k8s_yaml_file_extensions');
         $regex = '/\.(' . preg_replace('/ +/', '|', preg_quote($extensions, NULL)) . ')$/i';
 
-        $idx = 0;
-        foreach ($files ?: [] as $file) {
+        for ($idx = 0; $idx < count($files); $idx++) {
+          $file = $files[$idx];
           $message = NULL;
           $validated = FALSE;
           $file_contents = file_get_contents($file->uri);
@@ -628,7 +628,7 @@ class K8sCloudLaunchTemplatePlugin extends CloudPluginBase implements CloudLaunc
               'files' => [],
             ];
           }
-          $form['yaml_files'][$directory]['files'][] = [
+          $form['yaml_files'][$directory]['files'][$idx] = [
             '#type' => 'details',
             '#title' => $file->filename,
             '#open' => !$validated,
@@ -667,7 +667,6 @@ class K8sCloudLaunchTemplatePlugin extends CloudPluginBase implements CloudLaunc
               '#default_value' => str_replace($tmp_dir_name . '/', '', $file->uri),
             ],
           ];
-          $idx++;
         }
       }