Hi could you describe how you were able to encounter this bug in detail? I'd love to recreate it and debug it! I'd need to know if you were using auto-save, how far you got in your save, and your process of deleting the save file as well as if you used the corrupt save loader or not!
There wasn't really much to performing the bug in general from what I remember. I remember that I deleted my save at the very next save point after Willow leaves you because I realised just how many things I'd missed. Afterwards I used the corrupt save loader and it reverted to the room right after you retrieve Umbra from her cage. I mistakenly walked to the left, which caused the game to get stuck on a blank screen where I couldn't do anything. I understand the last part of it probably isn't important due to being a bug caused by a bug, but I just thought I'd mention it anyway.
I believe this glitch is caused by the save loader! I haven't tested it 100% since it's a bit difficult to recreate but jumping between v0.6-v0.7 using the save loader is a bit glitchy given I altered how saving works between those updates. I'm going to try and release a chapter selector or something next update that will help with corrupt save files