Unknown currency crashes the app when formatting

[Fatxx]

Describe the bug
Not all currencies are being properly formatted which further causes an application crash.

Screenshots

To Reproduce
TDB

Expected behavior
A clear and concise description of what you expected to happen

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• App Version [e.g. 1.0.0] - find version number in app from Settings > About MetaMask

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to be added after bug submission by internal support / PM
Severity

• How critical is the impact of this bug on a user?
• Add stats if available on % of customers impacted
• Is this visible to all users?
• Is this tech debt?

[Fatxx]

Duplicated of #4107