Make purefa_pgsnap module handle its own exit correctly

(cherry picked from commit d4c0269fbb)

changelogs/fragments/56954-purefa_pgsnap_handle_exit_correctly.yaml

@@ -0,0 +1,2 @@
+bugfixes:
+ - "purefa_pgsnap - handle exit correctly if selected remote volume or snapshot does not exist."

lib/ansible/modules/storage/purestorage/purefa_pgsnap.py

@@ -235,8 +235,12 @@ def main():
         module.fail_json(msg="Selected volume {0} does not exist in the Protection Group".format(module.params['name']))
     if ":" in module.params['name']:
         rvolume = get_rpgsnapshot(module, array)
+        if rvolume is None:
+            module.fail_json(msg="Selected restore snapshot {0} does not exist in the Protection Group".format(module.params['restore']))
     else:
         rvolume = get_pgroupvolume(module, array)
+        if rvolume is None:
+            module.fail_json(msg="Selected restore volume {0} does not exist in the Protection Group".format(module.params['restore']))
 
     if state == 'copy' and rvolume:
         restore_pgsnapvolume(module, array)
@@ -251,6 +255,8 @@ def main():
     elif state == 'absent' and not pgsnap:
         module.exit_json(changed=False)
 
+    module.exit_json(changed=False)
+
 
 if __name__ == '__main__':
     main()