Not sure why it’s not working based on what’s visible in the sketch you posted. But I’m guessing there’s something happening in the TM1637Display library that is looking for return data or confirmation from the display in order for the sketch to continue, so without the display plugged into your Stalker, the sketch hangs and stops, rather than ignoring the lost display and moving on.
I’d recommend something like this display: https://shop.switchdoc.com/products/grove-128×64-i2c-oled-board-for-arduino-and-raspberry-pi
It uses much lower power, you can remove it at any time from the board while the sketch is running and it won’t interrupt things. It has a Grove jack on it, so you can just connect it to one of the Grove ports on your Stalker (or our Mayfly) with a basic Grove cable (they come in various lengths).