Fix a bad dataState value when an error occurs on a deferred field that bubbles to the defer boundary

.changeset/loud-bulldogs-pay.md

@@ -0,0 +1,5 @@
+---
+"@apollo/client": patch
+---
+
+Fix an issue where a `@defer` query reported the `dataState` as `complete` instead of `streaming` when an error occurs on a deferred field that bubbled to the defer boundary.

src/core/QueryInfo.ts

@@ -399,8 +399,8 @@ export class QueryInfo<
 
           if (
             dataState === "complete" ||
-            (returnPartialData && dataState === "partial" && shouldWrite) ||
-            (this.hasNext && dataState === "streaming")
+            dataState === "streaming" ||
+            (returnPartialData && dataState === "partial" && shouldWrite)
           ) {
             result = { ...result, data: diffResult, dataState };
           }

src/incremental/handlers/__tests__/graphql17Alpha9/defer.test.ts

@@ -2506,13 +2506,13 @@ test("stream that returns an error but continues to stream", async () => {
 
   await expect(observableStream).toEmitTypedValue({
     loading: false,
-    data: {
+    data: markAsStreaming({
       hero: {
         __typename: "Hero",
         id: "1",
         name: "slow",
       },
-    },
+    }),
     error: new CombinedGraphQLErrors({
       data: {
         hero: {
@@ -2529,9 +2529,9 @@ test("stream that returns an error but continues to stream", async () => {
         },
       ],
     }),
-    dataState: "complete",
+    dataState: "streaming",
     networkStatus: NetworkStatus.error,
-    partial: false,
+    partial: true,
   });
 });