It makes perfect sense if the Lang objective is to fail as little as possible. It picks the left side object, checks if the operand is a valid operand of the type. If it is, it casts the right variable into that type and perform the operand. If it isn’t, it reverses operand positions and tries again.
The issue here is more the fact that + is used both as addition and as concatenation with different data types. Well, not an issue, just some people will complain.
The thing is that that kind of information is usually in the offer. I’d be polite and and for confirmation and clarification but not everyone has that kind of tact and not hiring someone because they didn’t ask you to repeat what it’s written on the offer is kinda harsh tbh.