There is an unfortunate signature change with the api.Context
NotFound function; whereas the normal modules/context/Context
NotFound function requires an error or nil, the api.Context
variant will panic with an NPE if a nil is provided.
This PR will allow api.Context.NotFound to tolerate a being
passed a nil.
Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: Lauris BH <lauris@nix.lv>