Any small change I make, even to the template one, breaks the tool. I keep getting this error message.
"Build error! TypeError: Cannot convert undefined or null to object"

Already tried switching browsers, but that did nothing? strange! Help appreciated. 

Hard to tell..? Is this with web version or downloadable one? And before you make a change, does the default font build and show up?

Sorry for being so vague! I tried both web and the downloadable versions, and the default font does build and show up^^ After even touching that 'character input' screen it stops working. I could get screenshots, but not sure if that really helps much.

And if you open the previous version on Wayback Machine, does that work?

https://web.archive.org/web/20250126224026/https://yal.cc/r/20/pixelfont/

Yeah this works well, no problems whatsoever! Thanks. Let me know if you need anything with tracking the bug, or something.

Hello. I'm seeing the exact same issue (same error message) with the new version. I have the previous downloadable version and it works fine for the same image and settings. Using up to date Chrome.

As of yet I have not been able to reproduce this in neither Firefox nor the 4 different Chromium-based browsers that I have installed so I’m kind of at loss as to what this could be.

I've just tried to reproduce the error using the same font image and settings, but have been unable to do it.  5 days ago, the issue was consistently happening for me using the offline and online versions.  I see that Chrome has updated itself since then...  In the meantime, I was able to get around the issue by using an older offline version.