If a teacher tells a student they never make a mistake, I would be highly skeptical of this person. I make goofy, annoying errors ALL the time. I also admit it. Case in point. I had students evaluate a series of points through a piecewise function. I made a typo. Because, typo.
I didn't catch it until some kid in the second testing class asked about it. The Desmos graph I built while writing the test was correct, I transcribed it wrong. There's three versions of the test, so I had to go hunting around the room to find who had the problem. One class took it completely unaware of the problem. Or, they adapted, like this kid. The way I wrote it they are correct in stating that h(-8) through h(-4) would be undefined in this case. Full credit for you. A few assumed it was a mistake and worked it as though it were written as intended.
It was especially goofy when they had to graph the h(x) they were given in the next section. Again, my bad.
Annoying, but manageable. Maybe I'll remember to fix this between now and a year from now when I test this subject again. There was a typo on the Calculus test I gave the same day. Sometimes I can't win. I managed to catch that one before I handed it out at least.