fix(sdk): accept blocks where coinbase is null (e.g. pending block)

[mask-pp]

1. Purpose or design rationale of this PR

• Appear error when getting a pending block, due to coinbase field is null.
• keep consistent with the behavior of the latest version of go-ethereum.

2. PR title

Your PR title must follow conventional commits (as we are doing squash merge for each PR), so it must start with one of the following types:

• build: Changes that affect the build system or external dependencies (example scopes: yarn, eslint, typescript)
• ci: Changes to our CI configuration files and scripts (example scopes: vercel, github, cypress)
• docs: Documentation-only changes
• feat: A new feature
• fix: A bug fix
• perf: A code change that improves performance
• refactor: A code change that doesn't fix a bug, or add a feature, or improves performance
• style: Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc)
• test: Adding missing tests or correcting existing tests

3. Deployment tag versioning

Has the version in params/version.go been updated?

• This PR doesn't involve a new deployment, git tag, docker image tag, and it doesn't affect traces
• Yes

4. Breaking change label

Does this PR have the breaking-change label?

• This PR is not a breaking change
• Yes

[colinlyguo]

Does this modification mean the header would not have the miner field?

[mask-pp]

Does this modification mean the header would not have the miner field?

Modified to be compatible with the case where the miner value is empty. And keep consistent with the behavior of the latest version of go-ethereum.

[colinlyguo]

Does this modification mean the header would not have the miner field?

Modified to be compatible with the case where the miner value is empty. And keep consistent with the behavior of the latest version of go-ethereum.

o i c.

[Thegaram]

Acceptable way to fix but the proper way would be to remove gencodec:"required" inside block.go

[mask-pp]

Acceptable way to fix but the proper way would be to remove gencodec:"required" inside block.go

Remove gencodec:"required" inside block.go and run gencodec -type Header -field-override headerMarshaling -out gen_header_json.go is the right way.