This web page is for building your sandwich order.
The "Your Selections" section is done very well by indicating the items that will be included and those that will not.
The special instructions field caused an error message that was not in plain language.
Help users recognize, diagnose, and recover from errorsError messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution.
https://www.nngroup.com/articles/ten-usability-heuristics/