fmusdk - SIGSEGV with ARC

[mantielero]

I have managed to structure fmusdk code using templates. But now it fails when 
I compile it using `--gc:arc`. It fails in the [first line of the first 
function](https://github.com/mantielero/fmi.nim/blob/4827727ced291fde10fed9b363ab8a0398f483d5/src/modelinstance.nim#L79)
 being called. 
    
    
    $ make
    ...
    /home/jose/src/fmi.nim/src/modelinstance.nim(79) fmi2Instantiate
    /home/jose/.choosenim/toolchains/nim-1.4.2/lib/system/arc.nim(63) nimIncRef
    SIGSEGV: Illegal storage access. (Attempt to read from nil?)
    
    
    Run

How can I investigate the source of the problem?

I am using a template (with `{.dirty.}`) to structure the code. How could that 
affect?