My suggested draft of a communication from and to someone at a company (which is not TW or a client of TW):
I would say "If you look at your error message, it's caused by the fact that in the code you sent me you hard-coded the path of a file in your program to find a test file in your own system. This is not acceptable. It also implies that you haven't done testing with a significant test set, which is also not acceptable. Please tell me what work you plan to do on the two technical errors, and your thoughts on what I/Company can do to help you improve your quality of work on this project."
I think that my feedback is too harsh. I think if the "This is not acceptable" was taken out it would be better. However, the person being addressed has shown a lack of knowledge such that there is a need for very clear statements about what code practices are not best practices.
There's rather a lot more in the above vein, but this is the part that makes me most wonder what more I have to learn about feedback.