Restore ErrorException for undef, fixes failing test
Compiling generic version

Bootstraps ok, but very slowly. Suspect it is dispatching back to jl_f_get_field for too many things.
Add getfield_sym (performance..?)
dead end. codegen: need to get rid of the static_eval before jl_apply_generic
band-aid for inference? this probably just hides the real problem

w/o this typeof( b[1:int(len[1])-1]) ) == Array{Any,1}. but typeof(b[1:10-1])) == Array{Uint8,1}.
this seems dumb.