[2.9] Handle post_validate templating errors and add tests (#70240) (#70390)

* Handle post_validate templating errors and fix tests (#70240)

* Handle unexpected templating errors

* Fixes #70050

Fix up tests that weren't running and add tests for graceful templating error handling

(cherry picked from commit 30e70f4b63)

* changelog

ci_complete

changelogs/fragments/70240-fix-fatal-post_validate-error.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - TaskExecutor - Handle unexpected errors as failed while post validating loops (https://github.com/ansible/ansible/issues/70050).

lib/ansible/executor/task_executor.py

@@ -584,7 +584,12 @@ class TaskExecutor:
             return dict(include_args=include_args)
 
         # Now we do final validation on the task, which sets all fields to their final values.
-        self._task.post_validate(templar=templar)
+        try:
+            self._task.post_validate(templar=templar)
+        except AnsibleError:
+            raise
+        except Exception:
+            return dict(changed=False, failed=True, _ansible_no_log=self._play_context.no_log, exception=to_text(traceback.format_exc()))
         if '_variable_params' in self._task.args:
             variable_params = self._task.args.pop('_variable_params')
             if isinstance(variable_params, dict):

test/integration/targets/lookups/tasks/errors.yml

@@ -0,0 +1,31 @@
+- name: Task that fails due to templating error for plugin option
+  debug: msg="{{ 5 / 0 | int }}"
+  ignore_errors: true
+  register: result
+
+- assert:
+    that:
+      - result.failed
+      - result.exception
+
+- name: Loop that fails due to templating error in first entry and ignores errors
+  debug: msg="{{ 5 / item }}"
+  ignore_errors: true
+  register: result
+  loop: [0, 0, 1]
+
+- debug: var=result
+
+- assert:
+    that:
+      - result.results[0].failed
+      - result.results[0].exception
+      - result.results[0].item == 0
+
+      - result.results[1].failed
+      - result.results[1].exception
+      - result.results[1].item == 0
+
+      - not result.results[2].failed
+      - result.results[2].exception is undefined
+      - result.results[2].item == 1

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

@@ -288,6 +288,8 @@
     that:
       - "hello_world_string|trim == 'Hello world!'"
 
+- include_tasks: ./errors.yml
+
 # Vars lookups
 
 - name: Test that we can give it a single value and receive a single value