Fix aspect attributes targeting PackageGroup.

A NullPointerException occured on such attributes while aspect was visiting target rule, because target rule had no such attribute.

RELNOTES: None.
PiperOrigin-RevId: 315272194
diff --git a/src/test/java/com/google/devtools/build/lib/analysis/AspectTest.java b/src/test/java/com/google/devtools/build/lib/analysis/AspectTest.java
index 2df81ba..8760a00 100644
--- a/src/test/java/com/google/devtools/build/lib/analysis/AspectTest.java
+++ b/src/test/java/com/google/devtools/build/lib/analysis/AspectTest.java
@@ -327,6 +327,17 @@
   }
 
   @Test
+  public void aspectDependsOnPackageGroup() throws Exception {
+    setRulesAvailableInTests(
+        TestAspects.BASE_RULE, TestAspects.PACKAGE_GROUP_ATTRIBUTE_ASPECT_RULE);
+    pkg("extra", "package_group(name='extra')");
+    pkg("a", "rule_with_package_group_deps_aspect(name='a', foo=[':b'])", "base(name='b')");
+
+    getConfiguredTarget("//a:a");
+    assertContainsEventWithFrequency("bad aspect", 0);
+  }
+
+  @Test
   public void aspectWithComputedAttribute() throws Exception {
     setRulesAvailableInTests(TestAspects.BASE_RULE, TestAspects.COMPUTED_ATTRIBUTE_ASPECT_RULE);