Return 400 for character encoding errors

[ericmj]

This is usually an input error from the user and should return a 400 error.

[SteffenDE]

Very nice! I've seen this a couple of times in production projects. In one case I even added a

    # postgrex crashes when it encounters a null byte in a text field,
    # therefore we replace any null bytes in the string
    email = String.replace(email, "\u0000", "")

Happy to remove this in the future 👍

[josevalim]

💚 💙 💜 💛 ❤️

[inoas]

Thank you!