buy rank shows incorrect upgrade cost for a moment than switching to correct value

[fierce onyx]

this wouldnt cause too much trouble but I just tried rapidly clicking the upgrade button, and then it ends like this

I think it was caused by some outdated level threshold, the game tries to load the old one, then updates to the new one by some update() per x frame function

if you click very fast you would be upgraded to the old level, which is 700 here