Fix mozilla#9741 bug(nimbus): Some of the FML errors are non-determin…

…istic and that is triggering the serialization repeatedly

experimenter/experimenter/experiments/api/v5/serializers.py

@@ -1,4 +1,5 @@
 import json
+import logging
 import re
 import typing
 from collections import defaultdict
@@ -41,6 +42,8 @@
 from experimenter.projects.models import Project
 from experimenter.settings import SIZING_DATA_KEY
 
+logger = logging.getLogger()
+
 
 class TransitionConstants:
     VALID_STATUS_TRANSITIONS = {
@@ -1441,11 +1444,9 @@ def _validate_feature_value_against_schema(
     def _validate_with_fml(self, feature_config, channel, obj):
         loader = NimbusFmlLoader(feature_config.application, channel)
         if fml_errors := loader.get_fml_errors(obj, feature_config.slug):
-            return [
-                f"{NimbusExperiment.ERROR_FML_VALIDATION}: "
-                f"{e.message} at line {e.line+1} column {e.col}"
-                for e in fml_errors
-            ]
+            for e in fml_errors:
+                logger.error(f"{e.message} at line {e.line+1} column {e.col}")
+            return [f"{NimbusExperiment.ERROR_FML_VALIDATION}"]
         return None
 
     def _validate_schema(self, obj, schema):