So I was playing Minecraft 1.12 with one of my friends on a LAN world. We were messing with custom items that we created using commands, and I created a custom item called the Object Eraser that has generic.attackdamage and generic.maxhealth of 999999 or something. But to get to that amount of health in survival quickly I also had to create a potion that has Instant Health 99999 or something. But to get it to heal the hearts(since the max health would disappear if I wasn't holding the Object Eraser) I would hover over the Object Eraser, swap hands, and then drink the potion. But the weird part was this: when I went to use the Object Eraser, the functions of the empty Glass Bottle where the potion was and the Object Eraser were swapped: the Glass Bottle did a ton of damage whereas the Object Eraser did nothing but normal punch damage. The only function that stayed the same was that when I right clicked with the Object Eraser it still placed a block(the Object Eraser was a barrier block for the texture). Anyone else have this glitch/am I just stupid and it's a really well known glitch? I was able to fix it by dropping the Object Eraser with Q and picking it back up(but I ended up placing a ton of random barrier blocks beforehand lol).