I’ve written enough compilers to know that you are at the mercy of the language often. It is hard to anticipate all mistakes, but if you are doing a language in which practically every string is legal, but with odd results, there is not much you can do.
I’ve made that mistake also, more than once. Experience means that you can scan for mistakes you tend to make and find them quickly.
The number of times I’ve had to pause while typing an unfamiliar function to puzzle out == vs =…
I good reason for me to keep adhering the the r paradigm of assignment being <-! The only time I get = vs == issues is inside function calls, and then it often helpfully says ‘Can’t do X. Did you use = instead of ==?’