fix(evm/rpc): prevent panic and fallback null responses in GetTransactionReceipt

[heejekim12]

Summary
This PR addresses several critical issues in the eth_getTransactionReceipt RPC method where calls frequently returned "result": null.

curl --location https://injectiveevm-testnet-rpc.polkachu.com \
--header 'Content-Type: application/json' \
--data '{
  "jsonrpc": "2.0",
  "method": "eth_getTransactionReceipt",
  "params": [
    "0x655d4fe0c8a06ea59b9e02cea4b9b5d245c26b6c30ce2d984f89b907bbccc011"
  ],
  "id": 1
}'

{"jsonrpc":"2.0","id":1,"result":null}

By improving array index bounds checking, adding error absorption during log decoding, enabling dynamic EVM index fallback, and enriching log metadata, this change enhances overall RPC stability and ensures full compliance with the standard Ethereum JSON-RPC specification.

Key Improvements & Fixes

1. Runtime Panic Prevention (Slice Out-of-Bounds Fix)

• Problem: Slicing blockRes.TxResults[0:res.TxIndex] directly caused index out of range panics when the number of TxResults in Tendermint was smaller than res.TxIndex.

• Fix: Introduced pre-checks and capped maxTxIndex against len(blockRes.TxResults) to guarantee safe slice access during cumulativeGasUsed calculation.

2. Graceful Handling of Log Decoding Failures

• Problem: When evmtypes.DecodeMsgLogs(...) failed due to malformed or incompatible Cosmos-SDK event logs, the error escalated immediately, aborting the entire request and returning null.

• Fix: Wrapped log decoding in an error-absorption block. Decoding failures are now safely logged as warnings, falling back to empty logs (logs: []) so that the core receipt payload is still returned successfully.

3. Complete Log Metadata Injection

• Problem: Successfully decoded log objects lacked critical Ethereum metadata fields (blockHash, txHash, txIndex, logIndex).
• Fix: Explicitly populated missing metadata fields onto each log object prior to constructing the final response payload.

4. Automatic EVM Index Recovery Fallback

• Problem: If the indexer DB failed to record EthTxIndex in time (EthTxIndex == -1), the call was aborted early with an error.
• Fix: Added a fallback mechanism (EthMsgsFromTendermintBlock) that dynamically inspects the block to recover the correct EVM transaction index on the fly.

5. Strict RPC Spec Alignment (contractAddress)

• Problem: Standard non-contract creation transactions omitted the contractAddress key entirely from the JSON response.
• Fix: Refactored payload construction to explicitly output "contractAddress": null when no contract is deployed, matching standard Ethereum JSON-RPC behavior.

[maxim-inj]

Hello, thanks for your contribution. I should note however that we are deprecating the built-in evm indexer, it's only for development purposes and not supported for production usage.

Please check https://github.com/InjectiveLabs/evm-gateway for the new way of serving the EVM endpoint backed by a node.

P.s. I will try to assess these improvements over evm-gateway, as it copied most of the old code..

[Copilot]

Pull request overview

This PR hardens the EVM JSON-RPC transaction lookup path—especially eth_getTransactionReceipt—to avoid panics and reduce result: null responses by adding bounds checks, introducing indexer fallbacks, and improving receipt/log formatting.

Changes:

• Added defensive bounds checks for TxIndex/MsgIndex access when decoding transactions and receipts.
• Implemented fallback behavior when the EVM index (EthTxIndex) is missing and made log decoding failures non-fatal.
• Enriched receipt output to better match Ethereum JSON-RPC conventions (e.g., contractAddress: null, log metadata population).

Comments suppressed due to low confidence (1)

injective-chain/modules/evm/rpc/backend/tx_info.go:71

• GetTransactionByHash returns an error when res.MsgIndex is out of range. For eth_getTransactionByHash, treating this as “not found” (returning nil, nil) is usually preferable to returning a JSON-RPC error due to indexer/event inconsistencies.

	msgs := tx.GetMsgs()
	if int(res.MsgIndex) >= len(msgs) {
		return nil, errors.New("msg index out of range")
	}

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[heejekim12]

@maxim-inj Thank you for responding. Please update testnet binary source code and tagging.