My hubby is terrible for this! He's cracked a little 40ltr before by dropping the water level, not turning the heaters off, then getting distracted.
The heat from the heaters combined with cold glass doesn't end well. You hear "CRACKBANGWOOSH" and there's water on the floor and fish everywhere.. Not good, and not fun to clean up.
He also messes around with the electrical outlets with wet hands, he hasn't been shocked by it YET, but I'm guna laugh when he does (given it doesn't seriously hurt him) and give him the most smart ath "I told you so" that ever was told.
I have a terrible habit of forgetting to dose prime until the tanks ¼ of the way full, thankfully I don't keep any extremely sensitive fish and no ones been hurt by it - yet...
I never add my water conditioner until the tank is completely full, turn on the power heads and let it circulate then turn on my filters 5 minutes later, always done it this way with stingrays, eels, knives and other sensitive fish, won't harm them in the length of time it takes to fill the tank