Add nicely.additionally

Should it actually modify the error object?

Signed-off-by: Eli Skeggs <skeggse@gmail.com>
Alter error object message property

Signed-off-by: Eli Skeggs <skeggse@gmail.com>
Add documentation and test for nicely.additionally

Signed-off-by: Eli Skeggs <skeggse@gmail.com>