feat/photon: prevent node runner to set uatone as only gas fees

[albttx]

When running node on #57 ( feat/photon ), if the RPC is set with uatone as a gas fees, outputs could be weird to understand.

here is an example:

$ atomoned tx bank send my-wallet atone1xxxx 500000000uatone --yes --fees 5000uatone
[...]
raw_log: 'fee denom uatone not allowed: invalid fee token'

$ atomoned tx bank send my-wallet atone1xxxxxx 500000000uatone --yes --fees 5000uphoton
[...]
raw_log: 'insufficient fees; got: 5000uphoton required: 200uatone: insufficient fee'

A warning at start of the node or enforce a default minimum-gas-fees with format 0.001uatone,0.001uphoton would be a good idea i believe.

[tbruyelle]

The first error is returned by the photon ante handler which only accepts PHOTON for the fee token.
The second error is returned by the cosmos-sdk TxFeeChecker which ensures that the fee tokens passed in the transaction are compliant with the minimum-gas-prices config of the node.

While this is a normal behavior, having them in a row like that is confusing I admit, even considering that the node operator has simply not followed the v2 upgrading procedure.

As you suggested, we could return an error if the minimum-gas-prices does not contain at least PHOTON, but that sets a kind of precedent, as this setting is usually left to the node operator. I am not sure if we should actually check it.

Wdyt @giunatale ?

[giunatale]

agreed with @tbruyelle