[Bug]: "f is not a function" error returned for wallet_addEthereumChain and wallet_switchEthereumChain

[norswap]

Describe the bug

This is reproducible accross all apps, and accross multiple browsers (Chrome & Firefox tested) on the latest version of the addon, try https://chainlist.org/ for instance.

The actual chain add works, but because an error is returned the apps will think that it didn't.

Expected behavior

The call does not return an error.

Screenshots/Recordings

Screenshot from chainlist:

Steps to reproduce

• Go to https://chainlist.org/
• Try to add or connect to any chain
• witness the error in your console

Error messages or log output

MetaMask - RPC Error: f is not a function 
Object { code: -32603, message: "f is not a function", data: {…} }
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code: -32603
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data: Object { cause: {…} }
​​
cause: Object { fileName: "moz-extension://897fa687-bf49-440d-af10-8d64d49b5cde/background-0.js", lineNumber: 1, columnNumber: 387156, … }
​​
<prototype>: Object { … }
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message: "f is not a function"
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<prototype>: Object { … }

Detection stage

In production (default)

Version

12.17.3

Build type

None

Browser

Firefox, Chrome

Operating system

MacOS, Linux

Hardware wallet

No response

Additional context

No response

Severity

No response