Where do nimErr's comes from?

[drkameleon]

I've been browsing through the generate sources in the Nim cache folder, and 
I've found many (many = I'm talking about roughly 23K lol) references and 
checks related to `nimErr_`:
    
    
    if (NIM_UNLIKELY(*nimErr_)) goto ...
    
    
    Run

Basically, it looks as if it's sprinkled around, especially after function 
calls - but I doubt it if every single one of its use cases is actually needed.

Any ideas where it's coming from and how/if I could selectively suppress some 
of them?