Every time I try to modify an internal script and test a level, Viridian does the freeze thing, but when I relaunch the game, it works again until I modify it again.
If it happens
Alt+enter
Esc
Place a trinket where Viridan spawns in the room (like on a checkpoint)
Enter the level and advance through the "you got a trinket!!!" text
Enter (to exit test mode)
Remove trinket
Also, it happens because you're pressing esc during a script that stops Viridan from moving.
That's why enter is also disabled, because enter is disabled during scripts
