fix(restore-indices): log error instead of silent failure (#15070)

Author: david-leifker

datahub-upgrade/src/main/java/com/linkedin/datahub/upgrade/restoreindices/SendMAEStep.java

@@ -224,6 +224,7 @@ public Function<UpgradeContext, UpgradeStepResult> executable() {
               context.report().addLine("End of data.");
               break;
             } else {
+              log.error("Failure processing restore indices batch.", e);
               return new DefaultUpgradeStepResult(id(), DataHubUpgradeState.FAILED);
             }
           }

datahub-upgrade/src/test/java/com/linkedin/datahub/upgrade/restoreindices/SendMAEStepTest.java

@@ -424,4 +424,27 @@ public void testExecutableWithCreateDefaultAspects() {
     RestoreIndicesArgs capturedArgs = argsCaptor.getValue();
     assertTrue(capturedArgs.createDefaultAspects);
   }
+
+  @Test
+  public void testExecutableWithNullResultFromFuture() {
+    // Insert test data to trigger processing
+    insertTestRows(5, null);
+
+    // Enable URN-based pagination to hit log.error in URN-based pagination path
+    parsedArgs.put(RestoreIndices.URN_BASED_PAGINATION_ARG_NAME, Optional.of("true"));
+
+    // Mock the entity service to throw an exception (not NoSuchElementException)
+    when(mockEntityService.restoreIndices(eq(mockOpContext), any(RestoreIndicesArgs.class), any()))
+        .thenThrow(new RuntimeException("Test exception"));
+
+    // Execute
+    UpgradeStepResult result = sendMAEStep.executable().apply(mockContext);
+
+    // Verify failure when exception is thrown in URN-based pagination
+    // This tests the log.error in the URN-based pagination path
+    assertTrue(result instanceof DefaultUpgradeStepResult);
+    assertEquals(result.result(), DataHubUpgradeState.FAILED);
+    assertEquals(result.stepId(), sendMAEStep.id());
+    assertEquals(result.action(), UpgradeStepResult.Action.CONTINUE);
+  }
 }