Once you realise this, you’ll never see the world the same again.

The senior developer swore the server was responding with a 500 because I, the co-op, was definitely sending the 'wrong encoding' whenever I post special characters. He said, "I'm only taking your data and putting it straight into the database!!!"

I found out it was breaking because he was converting the JSON payload to a STRING and simplistically separating the keys and values by colons and double quotes. Yuuup. Nothing can go wrong there...