Specially handle None and convert it to string

Author: Dimitar Tasev

queue_processors/queue_processor/instrument_variable_utils.py

@@ -249,6 +249,10 @@ def variable_was_updated(variable, new_value: Any, new_type: str, new_help_text:
         changed = False
         # compare the new value, which was converted earlier, to the original value in its real type
         real_type_value = VariableUtils.convert_variable_to_type(variable.value, variable.type)
+        # special case for a None value - make it a None string
+        if new_value is None:
+            new_value = "None"
+
         if new_value != real_type_value:
             variable.value = new_value
             changed = True