How does ethers react on HTTP 500 for 'eth_feeHistory' if constructing a transaction?

[chrisdotn]

From what I'm understanding about EIP1559 transactions, ethers does an eth_feeHistory. If the provider answers with a HTTP 400, ethers assumes that the network isn't supporting EIP1559 and revert to a legacy transaction. Is that the correct understanding?

What would happen if a provider responds with a HTTP 500 to the eth_feeHistory. I believe ethers would bail on the entire transaction. Or would it also revert to a legacy tx in that case?

(Apologies if an issue isn't the right format to ask these questions, feel free to redirect me to something else)

[ricmoo]

Ethers actually uses .getBlock to determine if the network is EIP-1559-enabled (the presence of a .baseFee indicates it is an EIP-1559 network).

Currently the feeHistory end-point is not used. The values used by querying the suggested priority fee and the latest block's base fee are used.