Prevent conditional templating errors from masking task output. Fixes #37187 (#74891)

changelogs/fragments/37187-catch-cond-tmpl-errors.yml

@@ -0,0 +1,4 @@
+bugfixes:
+- >-
+  ``failed_when``/``changed_when`` - Catch templating errors to prevent masking of module output
+  (https://github.com/ansible/ansible/issues/37187)

lib/ansible/executor/task_executor.py

@@ -671,8 +671,14 @@ class TaskExecutor:
             # if we didn't skip this task, use the helpers to evaluate the changed/
             # failed_when properties
             if 'skipped' not in result:
-                _evaluate_changed_when_result(result)
+                try:
-                _evaluate_failed_when_result(result)
+                    condname = 'changed'
+                    _evaluate_changed_when_result(result)
+                    condname = 'failed'
+                    _evaluate_failed_when_result(result)
+                except AnsibleError as e:
+                    result['failed'] = True
+                    result['%s_when_result' % condname] = to_text(e)
 
             if retries > 1:
                 cond = Conditional(loader=self._loader)

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

@@ -59,3 +59,15 @@
   assert:
     that:
       - groupby is not changed
+
+- name: invalid conditional
+  command: echo foo
+  changed_when: boomboomboom
+  register: invalid_conditional
+  ignore_errors: true
+
+- assert:
+    that:
+      - invalid_conditional is failed
+      - invalid_conditional.stdout is defined
+      - invalid_conditional.changed_when_result is contains('boomboomboom')

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

@@ -66,3 +66,15 @@
     that:
       - "'failed' in result and not result.failed"
       - "'failed_when_result' in result and not result.failed_when_result"
+
+- name: invalid conditional
+  command: echo foo
+  failed_when: boomboomboom
+  register: invalid_conditional
+  ignore_errors: true
+
+- assert:
+    that:
+      - invalid_conditional is failed
+      - invalid_conditional.stdout is defined
+      - invalid_conditional.failed_when_result is contains('boomboomboom')