try/catch doesn't work with C interop and structs

[geekrelief]

I've been working with a C library, and the try/catch mechanism doesn't work well for digging into structs.

For example, I call function that returns a ptr.

  let draw: ptr tm_creation_graph_draw_call_data_t = render_component_api.draw_call(...)

  if ?draw.shader: 
    # do stuff

If draw is nil then I'll get a crash because the access violation is coming from C and not from Nim. My work around is to use my conditional access macro that does checks at each step.

  if ?draw.?shader:
    # do stuff