OK, that was interesting. I stripped down the components (remember I said about minimal working example of the error) and ended up just with your text components called left_ and right_. By then the script was small enough that I could view what was going on in the script. Weirdly, left_ and right_ did not exist there!
So, it turns out that when the JS code is being generated the final underscore was being removed when the code is generated! That meant there was a clash between the variable left and the text object left which recursively tried to set itself to itself!
So, I need to work out why your underscore was being removed but the workaround at your end is to call the text Component something like left_txt rather than left_