You could say that. It was actually a trap, you must have stepped on some manner of pressure plate that activated it.

[He reaches down, pulling up the blowdart and showing it to Asriel. If he could even see it.]

It seems the trap was meant to tranquilize, not kill. Otherwise you'd be...

[Mettaton doesn't finish his sentence. He's too concerned to do such a thing. Besides, who wants to hear 'otherwise you'd be much sicker than this, I think'.]

...Point being, it's time to wake up. I'll bring you back to camp, and we will see if there is anything the medically inclined can do for you, alright?