don't bail on zero variance

Author: CamDavidsonPilon

core/pioreactor/background_jobs/growth_rate_calculating.py

@@ -242,9 +242,6 @@ def get_precomputed_values(
             self.logger.error(
                 "OD variance is zero - this suggests that the OD sensor is not working properly, or a calibration is wrong."
             )
-            raise ValueError(
-                "OD variance is zero - this suggests that the OD sensor is not working properly, or a calibration is wrong."
-            )
 
         if not self.ignore_cache:
             od_blank = self.get_od_blank_from_cache()

core/tests/test_growth_rate_calculating.py

@@ -190,16 +190,10 @@ def test_restart(self) -> None:
             config, [("od_config.photodiode_channel", "1", "90"), ("od_config.photodiode_channel", "2", "90")]
         ):
             with local_persistent_storage("od_normalization_mean") as cache:
-                cache[experiment] = json.dumps({1: 1, 2: 1})
+                cache[experiment] = json.dumps({"1": 1.15, "2": 0.93})
 
             with local_persistent_storage("od_normalization_variance") as cache:
-                cache[experiment] = json.dumps({1: 1, 2: 1})
-
-            with local_persistent_storage("od_normalization_mean") as cache:
-                cache[experiment] = '{"1": 1.15, "2": 0.93}'
-
-            with local_persistent_storage("od_normalization_variance") as cache:
-                cache[experiment] = '{"1": 1, "2": 1}'
+                cache[experiment] = json.dumps({"1": 1, "2": 1})
 
             od_stream, dosing_stream = create_od_stream_from_mqtt(
                 unit, experiment

web/pioreactorui/api.py

@@ -1771,7 +1771,6 @@ def delete_experiment(experiment: str) -> ResponseReturnValue:
         return {"status": "success"}, 200
     else:
         abort(404, f"Experiment {experiment} not found")
-    pass
 
 
 @api.route("/experiments/latest", methods=["GET"])