nit: Give helpful error messages for commands (e.g. `linear issue list`) when `linear config` is not ran.

[aderk]

Current behavior (before successful linear config):

[I] ad@Alans-MacBook-Pro ~/c/prophetic-alder (alder)> linear issue list
Sort must be provided via command line flag, configuration file, or LINEAR_ISSUE_SORT environment variable
[I] ad@Alans-MacBook-Pro ~/c/prophetic-alder (alder) [1]> linear issue start
Could not determine team ID

Desired behavior:
A helpful error message including something like "Do you need to run linear config?"

[schpet]

yes: thanks for pointing this out!

i'll note that this cli works unconfigured as well - which will require a --team flag IIRC) so message might need to cover that use case as well.