https://gist.github.com/BrassHerbologist/87435159feee640f0b9370262ac3e5ef

minecolonies-0.13.360-BETA-universal.jar for 1.16.3

structurize-0.13.92-ALPHA-universal.jar for 1.16.3

How to recreate this error:
1-load a new world, place a townhall and start your colony to spawn citizens
2-place a builder hut, wait for the builder to be hired
3-choose schematic for builders hut then start the build
4-recall him to his station then open his dialogue
5-here he will show you a list of what he needs
NOTE average crash time: around 50% completed builders hut
talking to the builder when his build is 50% done (has happened at 0% upon the first material request but tends to show more around 50%)
6-closing his material request screen brings you to his stats
7-upon hitting this screen, the UI will freeze, the cursor will show low framefrate and choppy trail before 'saving world' appears
8-the game will crash and reveal this exit code:

The game crashed whilst mouseclicked event handler
Error: java.lang.NullPointerException: mouseClicked event handler
Exit Code: -1

I am not good to diagnosing errors but this as much info as I have to work with

H3lay I'm sorry if this doesn't suffice, I've never really reported mod errors officially

Some other mod you've added must be causing this. can you figure out which by selectively removing them?

Optifine's installed, could it be that?

Unlikely, I suspect a tool mod.

@BrassHerbologist did you have time finding out which mod causes this?

You should try it out without them and if it works fine without them, report it to these mods and say they are not setting up their tool types correctly.