* If the user tried to run `/bank` with no arguments to see the current
value while disconnected, previously it threw an exception `KeyError:
'EnergyLinkNone'`. Now it informs the user that they must be connected
and in-game, like `/bank deposit` and `/bank withdraw` do.
I'm also open to adding another `if` branch to make `/bank` only check
for `ctx.server` instead of combining it with the other bank commands,
to allow connecting to check the bank before the game save is loaded.
If that's preferred let me know.
* If the user tried to run `/bank` or `/bank deposit` when the EnergyLink
hadn't been used yet, they would get a `TypeError` exception. Trying
`/bank withdraw` would give no output and would crash the lua
connector script. Now it treats a `None` EnergyLink as `0` and works
properly.