If a ground ball is hit to an infielder and the ball bounces off the glove and into the players upper body or face and the player is hurt and cannot make the play is it an error or a base hit?

If the ball took a bad hop and hit the fielders glove and then hit the fielder, there would not be an error and the batter would get credit for a hit. However if the fielder had the ball glance of the heel of his glove and come up and hit him in the face because he misplayed it, it should be scored as an error. To answer you question. Like any hit/error decision, this is soley up to the decision the Official Scorer makes. It is his job to determine whether the play should have been handled correctly and recorded an out, or if, the batter deserves a base hit.

** In MLB an injury will not stop the play until the play is over. i.e if an outfielder rolls an ankel going over a ball, they will not stop the play due to his injury, someone else will need to field the ball or all runners will score and then the play will end