Warning for command matching no packages?

[AlabasterAxe]

I think it might be useful to issue a warning or fail if a command specifies a package spec that matches no packages in the workspace. In my case, the directory of the package didn't match the name field in the package.json

Steps to repro:

• attempt to run a command specifying a package that doesn't exist in the workspace e.g. wsrun -p nonexistent -c build

Expected Behavior:

• this command doesn't map to any packages in the workspace so should error (potentially in a supressable way --allow-empty-package-list?, names are hard 🙃 )

Actual Behavior:

• the command immediately completes, reporting success