🐛 [#5035] Avoid the total configuration wrapper mutating the first st…

…ep configuration

The total configuration wrapper merges the configuration wrapper of
each step into a single object for optimized access to values/
components. It takes the first step and merges the remaining steps into
it. However, this had the unintended side-effect of mutating the config
of the first step, manifesting in the objects API v1 registration with
the json_summary tag which contained extra, unexpected keys in the
submission data of the first step.

Fixed by making a deep copy first to end up with a different instance
that can be safely mutated.

src/openforms/submissions/models/submission.py

@@ -2,6 +2,7 @@
 
 import logging
 import uuid
+from copy import deepcopy
 from dataclasses import dataclass
 from typing import TYPE_CHECKING, Any, Mapping
 
@@ -429,9 +430,8 @@ def total_configuration_wrapper(self) -> FormioConfigurationWrapper:
             if len(form_steps) == 0:
                 return FormioConfigurationWrapper(configuration={})
 
-            wrapper = FormioConfigurationWrapper(
-                form_steps[0].form_definition.configuration
-            )
+            begin_configuration = deepcopy(form_steps[0].form_definition.configuration)
+            wrapper = FormioConfigurationWrapper(begin_configuration)
             for form_step in form_steps[1:]:
                 wrapper += form_step.form_definition.configuration_wrapper
             self._total_configuration_wrapper = wrapper