Capture non-ftv1 errors in metrics (#2242)

This commit precedes apollographql/apollo-server#7136

For the mentioned PR (full context within), the gateway needs to capture error information from subgraphs with no trace data separately and report them within the metrics object that's shared with the inline trace plugin.

This change only takes effect for subgraphs with no ftv1 support or when fieldLevelInstrumentation on the inline trace plugin is set to 0 or returns 0.

.changeset/large-hornets-watch.md

@@ -0,0 +1,12 @@
+---
+"@apollo/gateway": patch
+---
+
+Capture non-ftv1 error information in metrics data. This
+error information allows the inline trace plugin to correctly
+aggregate stats about errors (where no federated trace data
+is available) and stop reporting incomplete traces which
+are missing unavailable error information.
+
+This PR is a precursor to apollographql/apollo-server#7136
+

gateway-js/package.json

@@ -28,7 +28,7 @@
     "@apollo/composition": "2.3.0",
     "@apollo/federation-internals": "2.3.0",
     "@apollo/query-planner": "2.3.0",
-    "@apollo/server-gateway-interface": "^1.0.2",
+    "@apollo/server-gateway-interface": "^1.1.0",
     "@apollo/usage-reporting-protobuf": "^4.0.0",
     "@apollo/utils.createhash": "^1.1.0",
     "@apollo/utils.fetcher": "^1.1.0",

gateway-js/src/__tests__/executeQueryPlan.test.ts

@@ -103,6 +103,7 @@ describe('executeQueryPlan', () => {
       request: {
         variables: {},
       },
+      metrics: {},
     };
   }
 

gateway-js/src/executeQueryPlan.ts

@@ -501,6 +501,18 @@ async function executeFetch(
         downstreamServiceError(error, fetch.serviceName, errorPathHelper),
       );
       context.errors.push(...errors);
+
+      if (!response.extensions?.ftv1) {
+        const errorPaths = response.errors.map((error) => ({
+          subgraph: fetch.serviceName,
+          path: error.path,
+        }));
+        if (context.requestContext.metrics.nonFtv1ErrorPaths) {
+          context.requestContext.metrics.nonFtv1ErrorPaths.push(...errorPaths);
+        } else {
+          context.requestContext.metrics.nonFtv1ErrorPaths = errorPaths;
+        }
+      }
     }
 
     // If we're capturing a trace for Studio, save the received trace into the