[Bug]: MM crashes during confirmations with some currencies

[bschorchit]

Describe the bug

MM crashes if user selects a currency that is not supported by the token api and starts a transaction that has simulation.

Expected behavior

Not crashing and displaying "Not available" if we're not able to get a conversion.

Screenshots/Recordings

Steps to reproduce

1. Go to Settings > General
2. Change your currency to Storj
3. Start a send transaction on Ethereum with any value
4. Notice MM crash

The only way to recover from the crash is to disable and re-enable MM and changing the network before unlocking it otherwise you'll consistently unlock it and arrive at the crashed screen

Error messages or log output

No response

Version

11.15.2

Build type

None

Browser

Brave

Operating system

MacOS

Hardware wallet

No response

Additional context

No response

Severity

No response