mgr/mgr_module: fix keyerror for op

If rule steps first element is opcode.

Fixes : https://tracker.ceph.com/issues/47272

Signed-off-by: Prashant Dhange <pdhange@redhat.com>

src/pybind/mgr/mgr_module.py

@@ -234,7 +234,7 @@ def get_rule_root(self, rule_name):
             return None
 
         try:
-            first_take = [s for s in rule['steps'] if s['op'] == 'take'][0]
+            first_take = [s for s in rule['steps'] if 'op' in s and s['op'] == 'take'][0]
         except IndexError:
             logging.warning("CRUSH rule '{0}' has no 'take' step".format(
                 rule_name))