It's hard to say from the perspective of an outsider without any actual knowledge of the used tone and the bug. But here is my advice: Would you have felt differently if that person would have used a different tone?
In general, you should be open and accept bug reports. Everyone introduces bugs all the time. That's why big companies have bug trackers. That's why there are "issues" on GitHub. Embrace them, thank the reporter (for even reporting it) and fix it. Then get on, it was just a bug.
If you, however, don't like the tone, and it's just the tone, then calmly and kindly tell the bug reporter that you personally do not like his choice of words, but thank them for reporting the bug and tell them you will fix it. Some people don't even realize that they sound harsh or inappropriate until you point it out to them.