When contract addresses that are not ERC-20 or ERC-721 were input, the token would be allowed to be added and would crash the app.
In addition, when an ERC-20 contract was deployed without a name and symbol, “Invalid ERC-20 address” would appear.
This PR adds error checking from the token detail lookup and reports the error back to the user in the modal. This prevents non-ERC-20/721 contracts from being able to be added to the app and prevents a crash.