So I just got an insight from my PW session in SQLplus. I finally understood why the fridge did the SQL console under Oracle return the error:
ORA-00911: invalid character
on a line that seemed perfectly correct, but it's as if it spawned you an invalid character, just because.
But in fact, when I enter a character unintentionally like ç, then I remove it, it's as if the text prompt makes it look like it got removed, but there's still the cedilla, or at least its character code roaming around in the line I'm writing, and thus resulting in an error.

I'm not even salty now, that got me curious, and I think it's better like this, even if I'll require a bit of research on that thing later on.