Salut VitN !
Not to worry - it's not nit-picking at all!
The contraction t'es is used in spoken French, but this isn't a "proper" contraction like, for example, changing le to l' when the following word starts with a vowel (e.g. l'école). For that reason, you won't see t'es in written texts; instead, you'll just hear it when people are speaking casually. Strictly speaking, it's not "correct," but it's so common that it's unavoidable when you're speaking to someone in an informal environment in French. It comes about simply because people tend to meld words together when they're speaking quickly - a lot like the contraction "I'd've" in English, which isn't a "proper" contraction either, but which you'll hear a lot in certain English-speaking regions.
I hope that this is helpful! Do let me know if you have any more questions on this!
À la prochaine,