breaking news— police chief says he will follow the law...
The rioters will not be so considerate. And some of the rioters will be carrying firearms. They will belligerently point out to adoring news crews that this is their right under the second amendment and Ohio state laws.
A planned ambush such as occurred in Dallas may be less likely as every suitable location will be filled with police officers. That will leave an insufficient number of men for area patrols.
The Convention may well be secured from armed attack. The routes to the area hotels will not be secure, and the delegates must generally be disarmed before they can enter the Convention. They likely won't be armed when they return to their hotels.
It is no great stretch of imagination to suppose that "protesters" will eventually cutoff a smaller group of delegates and physically attack them. At some point shots will be fired and people will be killed.
Which side incurs the casualties will not really matter. The News Media will spin the same conclusions in any case.
Preventing this kind of "random incident" will require very aggressive patrols around the area hotels and restaurants. My guess is that they will be short-staffed for this.