What did you do?
start new game, get resources to make an inserter, make an inserter, put it down,
opened an inserter, checked 'override stack size', changed the number from '1' to 't'
What happened?
The game crashes.
The factorio log recognises the game crashed, but seems unable to generate a symbolized stack trace. The last line before the crash is:
(note: 't' is the character i triet to enter into the number field.)111.170 Error RuntimeError.cpp:24: Unknown variable 't' at position 0 near 't'.
What did you expect to happen instead?
The expected behaviour is for the input field to reject or ignore the invalid input, and the game to continue as if nothing happened.
Does it happen always, once, or sometimes?
Happens always. To reproduce, open up an inserter and change the stack size to 't'. The game will crash. (same with all the other examples, but an inserter can be crafted minutes after starting the game.
attached log i started a new game with only the space age mods enabled, grabbed some iron plates, smelted some copper, crafted an inserter, put it down, changed the stack size to 't'.