So warning shots are reckless, but shooting people directly is not? My guess is, that there were about zero injuries because of these 49 warning shots. How many unarmed people have been shot in comparison by US police?
Note that some evidence suggests she was also the initial aggressor, which likely contributed to her conviction.
The chance of someone being injured by a "warning shot" is essentially the proportion of the ground surface which is occupied by a person. Unless you're in a crowded area, this is very low - in fact I would think it's less likely than a bystander being struck by a horizontally-fired bullet that misses its intended target.
Also warning shot is frequently likely to prevent the harm on the person that otherwise would be shot. Isn't it enough?