better missing editor message

fixes #10182

lib/ansible/utils/vault.py

@@ -203,7 +203,10 @@ class VaultEditor(object):
             self.write_data(existing_data, tmp_path)
 
         # drop the user into an editor on the tmp file
-        call(self._editor_shell_command(tmp_path))
+        try:
+            call(self._editor_shell_command(tmp_path))
+        except OSError, e:
+           raise Exception("Failed to open editor (%s): %s" % (self._editor_shell_command(tmp_path)[0],str(e)))
         tmpdata = self.read_data(tmp_path)
 
         # create new vault