This is unlikely to be a problem with the file. More likely, as the error message says, you’re having problems with the thermistor being improperly seated or intermittently losing its connection to the rest of the machine. It’s also possible that there’s a more serious hardware defect with your Snapmaker and the nozzle is actually not staying heated. For that, you’ll need to contact support (be warned that support is understaffed and very slow, but if you prod them enough, they’ll come through eventually).
Changing the nozzle assembly for a spare may be one quick thing you can try (it can’t hurt, anyway).
See Whats wrong with this picture - printre hot ends, A350 Nozzle Temp Issues, and other forum search results on “thermistor”.