It would be better if programmer can highlight particular error in red or some particular other than bold black one. Allow highlighting certain bits of a code fragment or quote has similar answer but I am not asking the same thing. I am asking for specific code for error.
I don't think that is particularly useful. We strive to have the shortest code necessary to reproduce the issue. If you have to highlight a specific line you are most likely having too much code.
I also expect this to get distracting very soon. I think posts will look like its christmas, not like a readable post. You can simply point to a line of code in a comment, like this:
int x = 1/0; // <-- error here
It is not a state-of-the-art solution, but it works like a charm. It is clear, doesn't distract. A winner to me.