After many tries I got a different exception log:

InvalidOperationException: Nullable object must have a value.
System.Nullable`1[T].get_Value () (at <a1e9f114a6e64f4eacb529fc802ec93d>:0)
DMD<Update>?-1024673664._LizardAI::Update (LizardAI this) (at <0a5b1206e2c0423a8cc5c632bc13d137>:0)
DMD<>?-1024673664.Trampoline<LizardAI::Update>?828686336 (LizardAI ) (at <6adea21db8bf469bbf6acda86367f0b9>:0)
SprobParasiticScug.LizardStuff.LizardAIUpdate (On.LizardAI+orig_Update orig, LizardAI self) (at <bbead1e3ad354a53b9170ee9d3ee886d>:0)
DMD<>?-1024673664.Hook<LizardAI::Update>?-1169216512 (LizardAI ) (at <640fa05ed3554dc7a947d37935470f0f>:0)
SprobParasiticScug.LizardStuff.LizardAct (On.Lizard+orig_Act orig, Lizard self) (at <bbead1e3ad354a53b9170ee9d3ee886d>:0)
DMD<>?-1024673664.Hook<Lizard::Act>?1209386496 (Lizard ) (at <acc1c1f1b5ef4a54a11859f28fc99efe>:0)
DMD<Update>?-1024673664._Lizard::Update (Lizard this, System.Boolean eu) (at <7960a3e1794d4c198a73ef47c75a1230>:0)
DMD<>?-1024673664.Trampoline<Lizard::Update>?2013139456 (Lizard , System.Boolean ) (at <771eea66a7bb4c3895658a302543683e>:0)
SprobParasiticScug.LizardStuff.LizardUpdate (On.Lizard+orig_Update orig, Lizard self, System.Boolean eu) (at <bbead1e3ad354a53b9170ee9d3ee886d>:0)
DMD<>?-1024673664.Hook<Lizard::Update>?807692288 (Lizard , System.Boolean ) (at <63635e13874947a88c95a52432027a6c>:0)
Room.Update () (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
RainWorldGame.Update () (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
MainLoopProcess.RawUpdate (System.Single dt) (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
RainWorldGame.RawUpdate (System.Single dt) (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
ProcessManager.Update (System.Single deltaTime) (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
RainWorld.Update () (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)

when did this one occur? or atleast what did you do to get this to show up?

and also, what lizard did you try to take control of?

I've been trying to test if I was just not properly doing what's required for bursting, so I've done nothing but press and hold those 3 keys (after filling my hunger of course).
The only other thing I can think of that could have caused it was when I attacked a Red Lizard as a dropwig and the game froze.

peculiar
in any case what mods do you have? perhaps a mod is doing a thing with this one

Actually, I play with a lot of mods, so every time I try to use this mod it gets stuck in the black screen after picking the campaign, so to test the mod I've been playing full vanilla.
The only mods I've been using are this one, Rain World Remix, More Slugcats & Input display, that last one was to check if I was messing up input.

can you use the health bars mod to see if trying to burst actually decreases the health or nah?

I tested, it doesn't

have you tried dying to a creature with max food?

I have, dying and getting dragged into a den turns me into the creature that caught me, I assume that's intentional.
But dying kicks me out from the corpse, so that works as intended.

good, atleast that means it isnt something with the bursting itself

i have since updated the mod to use a different way of bursting, though with the same keybinds, i recommend you try it if you get the time

NO WAY, I SEE WHAT'S HAPPENING

It's not that the key combination doesn't work, it's that it only works with the default buttons (Z, SHIFT & SPACE), so if I were to change my key to, for example: J, K and ENTER then It doesn't work

b ruh