[coverage] improve test coverage for indexed_items lookup (#74548)

test/integration/targets/lookup_indexed_items/tasks/main.yml

@@ -14,3 +14,19 @@
         - "x2 == 'set'"
         - "x3 == 'set'"
         - "x4 == 'set'"
+
+- block:
+    - name: "EXPECTED FAILURE - test not a list"
+      debug:
+        msg: "{{ item.0 }} is {{ item.1 }}"
+      with_indexed_items:
+        "a": 1
+
+    - fail:
+        msg: "should not get here"
+
+  rescue:
+    - assert:
+        that:
+          - ansible_failed_task.name == "EXPECTED FAILURE - test not a list"
+          - ansible_failed_result.msg == "with_indexed_items expects a list"