Use default on undefined vars in tests. (#17601)

test/integration/roles/test_conditionals/tasks/main.yml

@@ -281,7 +281,7 @@
 - block:
   - name: test a with_items loop using a variable with a missing attribute
     debug: var=item
-    with_items: "{{cond_bad_attribute.results}}"
+    with_items: "{{cond_bad_attribute.results | default('')}}"
     register: result
   - set_fact: skipped_bad_attribute=False
   - name: assert the task was skipped

test/integration/vars_file.yml

@@ -8,5 +8,5 @@ things1:
     - 2
 things2:
     - "{{ foo }}"
-    - "{{ foob }}"
+    - "{{ foob | default('') }}"
 vars_file_var: 321