python error when using 'sudo snappy install' with no args

[Chris J Arges]

$ sudo snappy install
Usage:snappy [-h] [-v]
             {info,versions,search,update-versions,update,rollback,install,uninstall,tags,build,chroot,framework,fake-version,nap}
             ...
Traceback (most recent call last):
  File "/usr/bin/snappy", line 9, in <module>
    status = Main().__main__()
  File "/usr/lib/python3/dist-packages/snappy/main.py", line 159, in __main__
    return callback(args)
  File "/usr/lib/python3/dist-packages/snappy/main.py", line 368, in _do_install
    + packages + [package]
UnboundLocalError: local variable 'package' referenced before assignment

Seems like we should catch this exception before and display usage or a warning to the user.

[Alexander Sack (asac)]

mvo: another case to wrap in our general console experience "error reporting"; need to design and make this clean.

[Michael Vogt (mvo)]

$ sudo snappy install
package name is required