Get UNEXPECTED ERROR When Post/Get/Put/Delete Any Data to a RESTlet

Scenario

Post any data to a restlet script and get this error

{
    "error": {
        "code": "UNEXPECTED_ERROR",
        "message": "Unsupported file extension: "
    }
}

Solution

This is due to no file extension on the script file. Make sure you appended .js file extension after File Name on the script file record, even if the File Type is JavaScript File already.