ethclient.Client#HeaderByNumber fails for pending block

[meowsbits]

System information

Geth version:

Geth
Version: 1.10.2-unstable
Git Commit: 91726e8aadeebc4bda8f136aebf4b5c7da8b9d74
Git Commit Date: 20210316
Architecture: amd64
Go Version: go1.16
Operating System: linux
GOPATH=/home/ia/go
GOROOT=/home/ia/go1.16.linux-amd64

Expected behaviour

ethclient.Client#HeaderByNumber(-1) returns a pending block header equivalent to the value returned by an external RPC call, eg. eth_getBlockByNumber("pending", false).

Actual behaviour

This method returns an error and an almost-empty header.
Error returned is: missing required field 'miner' for Header", want %!q(<nil>), though this will not be the only issue since the types.Header JSON unmarshaling methods are not able to handle consensus-invalid headers.
Below, a JSON-encoded example of the response.

{
    "parentHash": "0x228d7580ae75567749daa5ed31ff1fcc09803ebe001b44f64b0f364c19bff4cb",
    "sha3Uncles": "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347",
    "miner": "0x0000000000000000000000000000000000000000",
    "stateRoot": "0x0000000000000000000000000000000000000000000000000000000000000000",
    "transactionsRoot": "0x0000000000000000000000000000000000000000000000000000000000000000",
    "receiptsRoot": "0x0000000000000000000000000000000000000000000000000000000000000000",
    "logsBloom": "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
    "difficulty": null,
    "number": null,
    "gasLimit": "0x0",
    "gasUsed": "0x0",
    "timestamp": "0x0",
    "extraData": "0x",
    "mixHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
    "nonce": "0x0000000000000000",
    "hash": "0xc5343d7f4960fbc487e877585726949b6a36150e3ed7cd0954741f467b98d0b8"
}

Steps to reproduce the behaviour

I've created a branch (and an adhoc PR) with additional ethclient tests demonstrating the issue here: #22515.

[ligi]

Can you tell us more about your use-case?

[meowsbits]

Closing since the PR resolving this issue is already closed as a "wont-fix" (#22517)