The error is quite precise.
rawMp3Data is seen as a void pointer, which you can delete, since type and thus memory size information is missing.
Why this is happening with a thread, I don't know, especially since I don't know what mouse_pos_loop does.
Personally recommendation: Don't use threads, unless you're an expert on the topic. There are a lot of complexities and issue that threads can introduce and more often than not, it doesn't actually solve the thing you imagined it would solve.