Can't generate bindings for libvips

[NARKOZ]

I'm trying to generate bindings for libvips:

GIRepository::Repository.instance.require "Vips"
Namespace.new("Vips").write "src/generated"             

but it throws error:

Nil assertion failed (Exception)          
0x10f34e1a5: *CallStack::unwind:Array(Pointer(Void)) at ?? 
0x10f34e141: *CallStack#initialize:Array(Pointer(Void)) at ??                                                          
0x10f34e118: *CallStack::new:CallStack at ??               
0x10f335c85: *raise<Exception>:NoReturn at ??              
0x10f335c31: *raise<String>:NoReturn at ??                 
0x10f37e363: *Nil#not_nil!:NoReturn at ??                  
0x10f36ed5b: *String#[]<Regex, Int32>:String at ??         
0x10f3b095b: *Namespace#lib_definition<File>:Nil at ??     
0x10f3b0609: *Namespace#write_lib<String>:Nil at ??        
0x10f3b0475: *Namespace#write<String>:Nil at ??            
0x10f335719: __crystal_main at ??                          
0x10f34aa98: main at ??  

Crystal version: 0.23.0 vips version: 8.5.6

[jhass]

Hey, it worked just fine for me, using Crystal 0.23.1, vips 8.5.6 & gobject-introspection 1.52.1. You can check the generated bindings (probably not bug free) in the vips branch.

What OS do you run?

[NARKOZ]

Mac OS Sierra