Issue #3117465: Fix notices when a release is unpublished

usage/project_usage.module

@@ -253,6 +253,10 @@ function project_usage_restws_response_alter(&$response, $function, $formatName,
           }
           foreach ($usage as $project_nid => $releases) {
             foreach ($releases as $nid => $count) {
+              if (!isset($release_branches[$nid])) {
+                // Release is unpublished, or otherwise missing.
+                continue;
+              }
               if (isset($response['list'][$nid_map[$project_nid]]['project_usage'][$release_branches[$nid]])) {
                 $response['list'][$nid_map[$project_nid]]['project_usage'][$release_branches[$nid]] += $count;
               }