[gameplay?] Tower range indicator starts expanding endlessly

https://gfycat.com/IncompletePolishedBaboon

I started a custom game of aram. Only me. I stood still for maybe 1-2 minutes next to the ennemy nexus turrets. Then the range indicator started expanding like this. I tried it again once so I could get the video, so I assume it must be easy to reproduce this. Not sure if it happens in other game modes, didn't try.

I didn't stay long afterwards but it didn't seem to reappear unless I left the area near the tower that shows it's range.