src/ir.cpp: add/throw error for @handle() in a non async context;
src/ir.cpp: add/throw error for @handle() in a non async context;

Tracking Issue #1296 ;
Thanks @andrewrk ;

raulgrell/zig,raulgrell/zig,raulgrell/zig,zig-lang/zig,andrewrk/zig,Dimenus/zig,raulgrell/zig,zig-lang/zig,raulgrell/zig,Dimenus/zig,zig-lang/zig,andrewrk/zig,Dimenus/zig