fix(datastore): List errors that are returned from AppSync (#2801)

Author: mattcreaser

aws-datastore/src/main/java/com/amplifyframework/datastore/syncengine/SyncProcessor.java

@@ -53,6 +53,7 @@
 import java.util.List;
 import java.util.Objects;
 import java.util.concurrent.atomic.AtomicReference;
+import java.util.stream.Collectors;
 
 import io.reactivex.rxjava3.core.Completable;
 import io.reactivex.rxjava3.core.Flowable;
@@ -320,8 +321,13 @@ private <T extends Model> Single<GraphQLResponse<PaginatedResult<ModelWithMetada
         return Single.create(emitter -> {
             Cancelable cancelable = appSync.sync(request, result -> {
                 if (!result.hasData()) {
+                    List<String> errorStrings = result.getErrors().stream()
+                                                    .map(GraphQLResponse.Error::toString)
+                                                    .collect(Collectors.toList());
+                    String errors = String.join(",\n", errorStrings);
+
                     emitter.onError(new DataStoreException.IrRecoverableException(
-                            "Empty response from AppSync.", "Report to AWS team."
+                            "Received errors from AppSync: " + errors, "Report to AWS team."
                     ));
                 } else {
                     if (result.hasErrors()) {