To me it still looks safe to reuse. Does it leak as is? The rear chip looks iffy, I don't think the tank will bust out or anything, but might leak slowly, but a good amount of silicone in it should seal it. I think just a reseal and it will be fine filled all the way.
I have a 20 gallon high that has a chip bigger than those pictured and it doesn't leak, didn't need to reseal either. But that is a 20gal, a 50gal is a lot more force on the panes and corners.
Fill it up as is, see for any leaks. If back corner leaks, reseal or just make another overflow at that corner (functional or not, with the overflow blocking the water, that actual tank corner has less force pushing against it).
Can't really lose either way unless the tank goes blow out (at least you can salvage some glass to DIY a small tank or make glass tops/lids. Vivariums/Paludariums are cool.