Description

A bug was introduced in #24415, where user rejected request errors are not correctly handled in either wallet_switchEthereumChain nor wallet_addEthereumChain calls.

Related issues

Fixes: Regression in API error handling found on a local run of the new API testing tool, will link report when available.

Manual testing steps

wallet_addEthereumChain

1. Go to https://docs.metamask.io/wallet/reference/wallet_addethereumchain/
2. Submit the prepopulated wallet_addEthereumChain request
3. Confirm the request to add Gnosis Chain
4. But click "Cancel" on the second request to switch to the newly added chain
5. You should see null as the response

wallet_switchEthereumChain

1. Make sure the wallet is on a chain other than gnosis
2. Go to https://docs.metamask.io/wallet/reference/wallet_switchethereumchain/
3. Submit the prepopulated switchEthereumChain request (for chainId: 0x64)
4. Click cancel on the request to switch to gnosis chain
5. you should see:

{
  "code": 4001,
  "message": "User rejected the request.",
  "stack": "{\n  \"code\": 4001,\n  \"message\": \"User rejected the request.\",\n  \"stack\": \"Error: User rejected the request.\\n  
 }

in the response

Screenshots/Recordings

Before

After

Pre-merge author checklist

• I've followed MetaMask Contributor Docs and MetaMask Extension Coding Standards.
• I've completed the PR template to the best of my ability
• I’ve included tests if applicable
• I’ve documented my code using JSDoc format if applicable
• I’ve applied the right labels on the PR (see labeling guidelines). Not required for external contributors.

Pre-merge reviewer checklist

• I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.