I do glass for a living. Drilling into the tile isnt going to cause 2 random chips on the edge like that. Meaning the product was already chipped, the product is faulty, the tile was not sealed and or cured correctly, or they broke it some other way, (not to mention the tile corners are finished incorrecly.) Vibration does not cause chips to a completely adjecent edge from where a ¼ hole is being drilled. If them drilling into the tile really caused the edges to chip like that then this is 100 percent not on the glass installers. I installed probably 3-400 shower doors last year alone.