Problem: Panic when calculating base fee for legacy block

[VictorTrustyDev]

https://github.com/crypto-org-chain/ethermint/blob/8ebf0e8b5d9c477804d4dbadad06ba56991c3d23/x/feemarket/keeper/eip1559.go#L104

MinGasPrice can be nil on legacy blocks thus this method will panic during tracing on legacy blocks.

Suggestion change: view this single commit

[mmsqe]

fixed by #1444