chore: checks if not undefined for non-evm conversion rates

[zone-live]

Description

Currently every time we initially create an account we get null values from formatNonEvmAssetCurrencyDisplay because the conversionRate is zero 0 for non-evm assets (BTC/SOL). And when this happens, since zero 0 evaluates as false we will get a null from the formatNonEvmAssetCurrencyDisplay method.
Therefore we need to allow the initial zero value and just make sure it's not undefined.

Related issues

Fixes:

Manual testing steps

You can try to do a fresh install of flask extension in branch main vs this one, and add a Solana account.

1. Checkout this branch and run yarn
2. Update the file shared/lib/accounts/solana-wallet-snap.ts with:
   export const SOLANA_WALLET_SNAP_ID: SnapId = 'local:http://localhost:8080' as SnapId;
3. Run the extension with yarn start:flask
4. Run the Snap: https://github.com/MetaMask/snap-solana-wallet
   • Clone it
   • Run yarn
   • Run yarn start
5. Go to http://localhost:3000/
6. Install the Snap
7. In the extension, go to the Settings > Experimental > Enable Solana account
8. Add a Solana account
9. Check for the UI differences

Screenshots/Recordings

Before

After

Pre-merge author checklist

• I've followed MetaMask Contributor Docs and MetaMask Extension Coding Standards.
• I've completed the PR template to the best of my ability
• I’ve included tests if applicable
• I’ve documented my code using JSDoc format if applicable
• I’ve applied the right labels on the PR (see labeling guidelines). Not required for external contributors.

Pre-merge reviewer checklist

• I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[metamaskbot]

Builds ready [038db1c]

• builds: chrome, firefox
• builds (flask): chrome, firefox
• builds (MMI): chrome
• builds (test): chrome, firefox
• builds (test-flask): chrome, firefox
• build viz: Build System
• mv3: Bundle Size Stats
• mv2: E2e Actions Stats
• storybook: Storybook
• typescript migration: Dashboard
• all artifacts
• bundle viz:

  • background: 0, 1, 2, 3, 4, 5, 6, 7
  • common: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13
  • ui: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12
  • content-script: 0
  • offscreen: 0

Page Load Metrics (1697 ± 68 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	1463	2102	1697	139	67
		domContentLoaded	1453	2071	1667	131	63
		load	1465	2106	1697	141	68
		domInteractive	24	68	33	13	6
		backgroundConnect	10	75	34	21	10
		firstReactRender	15	96	34	26	12
		getState	4	64	15	18	8
		initialActions	0	1	0	0	0
		loadScripts	1045	1531	1218	117	56
		setupStore	7	56	16	16	8
		uiStartup	1791	2389	1963	136	65

Bundle size diffs [🚨 Warning! Bundle size has increased!]

• background: 0 Bytes (0.00%)
• ui: 0 Bytes (0.00%)
• common: 12 Bytes (0.00%)