You are correct. I disabled the settings and i can now type 't' in numeric fields without crashing.

I saw other posts which referenced this particular source file and this solution. Apologies I didn't realise I have turned this option on.

Should I do something to close this report?

Inserting a character not parsable as part of a number into an inserters 'override stack size' crashes the game. The same happens when the amount in a requester chest or the number field on a decider combinator is changed to something that is not a number (e.g. the letter 't').

What did you do ...