Fork Uniswap for a new Ethereum chain gives MetaMask - RPC Error

[Ben-Haslam]

Bug Description

I have forked the Uniswap interface for a private ethereum network, by adding another chain Id that the interface can use and modifying the right addresses. (this means rebuilding the sdk too and importing the dist into the uniswap-interface node modules. )

Upon loading the development build of the interface and connecting to a metamask wallet, the interface initially appears successful, displaying the balance of ETH and tokens, but then after a few seconds loses connection. If I look at the console in browser, I see that when it loses connection, I get the following error:

If anybody has seen this problem before and might know how to fix it I would be extremely thankful!

Steps to Reproduce

1. Go to the repo for the forked interface here, or make your own fork for a new Ethereum network
2. Run the script script.sh

Expected Behavior
The interface should work with the Autontiy Bakerloo network (or another network it has been forked for) without losing connection and giving this error.

Additional Context

I have also tried using a repo made by @tpmccallum to do the same thing here which led to the same outcome.

I believe I am not alone in having this error when attempting to fork the interface for another network, as these issues show the same problem:

sky-ecosystem/multicall#14
second-state/how_to_deploy_uniswap#4