Python conditional fails to reach the else statement when the if statement is not satisfied

try:
            symbol = input("Specify symbol: ").upper()
            dt_string = input("Specify datetime in isoformat (e.g.'2021-05-27T03:30:00+00:00'): ")
            try:
                dt = datetime.fromisoformat(dt_string)
            except Exception as e:
                print(e)
            ts = Decimal(input("Specify ticksize after: "))
        except Exception as e:
            print(e)
        else:
            with open(join(file_directory, "ticksize_changes.json"), "r") as f:
                ts_dict = json.load(f)
                print(ts_dict)
                if ts_dict[symbol]: # if symbol exists in json file
                    ts_dict[symbol].append({'datetime': dt_string, 'ts_after': ts})
                else:
                    ts_dict[symbol] = [{'datetime': dt_string, 'ts_after': ts}]
            with open(join(file_directory, "ticksize_changes.json"), "w") as f:
                json.dump(ts_dict, f, default=str)

I have a try-except-else structure, and in the else, I have a with statement. In that with statement, I have a simple if-else. I tried a case where the if statement executed successfully, but as soon as I tried a case where it should reach the else statement I get the following error:

The console message is correct - indeed no such key exists. But why does the else statement fail to execute?

you should use this statement, first make sure the dictionary keys containing it.

if symbol in ts_dict.keys(): # if symbol exists in json file
    ts_dict[symbol].append({'datetime': dt_string, 'ts_after': ts})
else:
    ts_dict[symbol] = [{'datetime': dt_string, 'ts_after': ts}]