fix(events): treat an error event without function calls as a final response

Matches adk-python: a complete event carrying an error code ends the turn
unless the model still asked for tools, even when it holds a function
response.

Author: Laurianti

core/src/main/java/com/google/adk/events/Event.java

@@ -353,6 +353,10 @@ public final boolean finalResponse() {
     if (actions().skipSummarization().orElse(false) || hasPendingLongRunningToolCall()) {
       return true;
     }
+    // An error ends the turn unless the model still asked for tools; mirrors Python ADK.
+    if (errorCode().isPresent() && !partial().orElse(false) && functionCalls().isEmpty()) {
+      return true;
+    }
     return functionCalls().isEmpty()
         && functionResponses().isEmpty()
         && !partial().orElse(false)

core/src/test/java/com/google/adk/events/EventTest.java

@@ -330,4 +330,62 @@ public void finalResponse_returnsTrueIfSkipSummarization() {
             .build();
     assertThat(event.finalResponse()).isTrue();
   }
+
+  @Test
+  public void finalResponse_isTrueForErrorEvent() {
+    Event event =
+        Event.builder()
+            .id("e1")
+            .invocationId("i1")
+            .author("agent")
+            .content(Content.fromParts(Part.fromText("hello")))
+            .errorCode(new FinishReason("SOME_ERROR"))
+            .errorMessage("Something went wrong")
+            .build();
+    assertThat(event.finalResponse()).isTrue();
+  }
+
+  @Test
+  public void finalResponse_isTrueForErrorEventWithFunctionResponse() {
+    Event event =
+        Event.builder()
+            .id("e1")
+            .invocationId("i1")
+            .author("agent")
+            .content(
+                Content.fromParts(Part.fromFunctionResponse("tool", ImmutableMap.of("k", "v"))))
+            .errorCode(new FinishReason("SOME_ERROR"))
+            .errorMessage("Something went wrong")
+            .build();
+    assertThat(event.finalResponse()).isTrue();
+  }
+
+  @Test
+  public void finalResponse_isFalseForErrorEventWithFunctionCall() {
+    Event event =
+        Event.builder()
+            .id("e1")
+            .invocationId("i1")
+            .author("agent")
+            .content(Content.fromParts(Part.fromFunctionCall("tool", ImmutableMap.of("k", "v"))))
+            .errorCode(new FinishReason("SOME_ERROR"))
+            .errorMessage("Something went wrong")
+            .build();
+    assertThat(event.finalResponse()).isFalse();
+  }
+
+  @Test
+  public void finalResponse_isFalseForPartialErrorEvent() {
+    Event event =
+        Event.builder()
+            .id("e1")
+            .invocationId("i1")
+            .author("agent")
+            .content(Content.fromParts(Part.fromText("hello")))
+            .errorCode(new FinishReason("SOME_ERROR"))
+            .errorMessage("Something went wrong")
+            .partial(true)
+            .build();
+    assertThat(event.finalResponse()).isFalse();
+  }
 }