fix: prevent nil pointer dereference in eth_simulateV1

[harshsingh-cs]

Add nil checks for BlockOverrides and StateOverrides before accessing their fields in processBlock(). This fixes a crash when eth_simulateV1 is called with minimal parameters that don't include these overrides.

The panic occurred at lines 237 and 242 where the code attempted to access nested fields without checking if the parent objects were nil.

Here is how we can reproduce

curl -s http://localhost:8545 -H 'content-type: application/json' \
--data '{
  "jsonrpc":"2.0",
  "id":1,
  "method":"eth_simulateV1",
  "params":[
    {"blockStateCalls":[{"calls":[{"from":"0x0000000000000000000000000000000000000000","to":"0x0000000000000000000000000000000000000000","data":"0x"}]}]},
    "latest"
  ]
}'
# => -32603 "method handler crashed"

Description

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Changes

• Bugfix (non-breaking change that solves an issue)
• Hotfix (change that solves an urgent issue, and requires immediate attention)
• New feature (non-breaking change that adds functionality)
• Breaking change (change that is not backwards-compatible and/or changes current functionality)
• Changes only for a subset of nodes

Breaking changes

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Nodes audience

In case this PR includes changes that must be applied only to a subset of nodes, please specify how you handled it (e.g. by adding a flag with a default value...)

Checklist

• I have added at least 2 reviewer or the whole pos-v1 team
• I have added sufficient documentation in code
• I will be resolving comments - if any - by pushing each fix in a separate commit and linking the commit hash in the comment reply
• Created a task in Jira and informed the team for implementation in Erigon client (if applicable)
• Includes RPC methods changes, and the Notion documentation has been updated

Cross repository changes

• This PR requires changes to heimdall
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• This PR requires changes to matic-cli
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Testing

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• I have added tests to CI
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• I have tested this code manually on remote devnet using express-cli
• I have tested this code manually on amoy
• I have created new e2e tests into express-cli

Manual tests

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Additional comments

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[kamuikatsurgi]

Hey, this is already merged via this #1955. Closing this as a dup. Thanks for the contribution.