"irregular" I mean like a value that is bigger then your actual monitor.
What exactly is your native monitor resolution?
What exactly did you enter for the window size?
At least on my system*, I can't reproduce your bug by specifying a window bigger than the native resolution. For the window size, I can put 4000 x 2000, which is bigger than my monitor's current and native resolution of 3440 x 1440. I get a window that is bigger than my screen as expected. It won't open and close.
*) 64-bit Linux with X (i.e., not Wayland) and Allegro 64-bit version 5.2.8, running 64-bit Linux Lix 0.10.19.
Lix's mouse cursor will be confined to roughly the top-left quarter, but that's a separate issue.
Neither can I reproduce the bug in Wine 8.21, running Windows Lix 0.10.19 64-bit on that same Linux machine. Difference though: The Lix window with Wine doesn't open as 4000 x 2000, it opens as 3440 x 1440, but still with a border, i.e., not a software fullscreen.
doesn't just close it like continually closes and opens again
Yes, this is a problem, and we should catch that.
At minimum, this bug locks you out of Lix's options menu. To recover, you can erase the options file, but some users won't think of that or find that file.
-- Simon