Copy-pasting what you have works, but I found that whenever I type 'v' in the Javascript version, it freezes up.
From the documentation, 'v' is supposed to rotate the top 3 items on the stack. If you're in TYX-video mode, there should be 3 items by default. The documentation also mentions that it's supposed to use T-video mode if it detects that, where there is only one item on the stack. Perhaps it's incorrectly detecting T-video mode and then running into problems when it tries to do the v-rotate past the end of the stack?
when the program parses the ibniz string, it seems to look for a character AFTER v. if v is the last character in the string, then when it does this , it gets undefined, attempts to get the char code for it, and thus throws an error since undefined isn't a string with a charCodeAt method. This is easily fixed by guarding that section of code to make sure that it always returns a string and never returns undefined.
From the documentation, 'v' is supposed to rotate the top 3 items on the stack. If you're in TYX-video mode, there should be 3 items by default. The documentation also mentions that it's supposed to use T-video mode if it detects that, where there is only one item on the stack. Perhaps it's incorrectly detecting T-video mode and then running into problems when it tries to do the v-rotate past the end of the stack?