fix: 0 token balance in send flow

[bergeron]

Description

Fixes an issue where token balance showed as 0 during send flow. This occurred when clicking the token in the token list, then clicking the send button from the token details page.

When going send first and then picking a token, picking decimals was a number:

But when going token first and then clicking send , decimals was a string and skipped calculating the balance.

calcTokenAmount seems to work with either string or number, so changing logic from #27083 which introduced the number check

Related issues

Fixes: #28112

Manual testing steps

1. Click on an erc20 token on the token list
2. Click the send button on the token details page
3. Choose a destination account
4. The balance under the asset picker should be accurate

Screenshots/Recordings

Before

After

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• I've completed the PR template to the best of my ability
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Pre-merge reviewer checklist

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[github-actions]

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[bergeron]

or maybe parseInt(details.decimals) >= 0. I'm not sure when this can be something unexpected. The number check was introduced to replace a truthiness check, which did not work for 0 decimal tokens.

[bergeron]

I did verify this PR still works for 0 decimal tokens

[legobeat]

This will also be false when balance === 0 - should change the details.balance to typeof details.balance, or is it typed well enough that we know that details.balance is never a number representation?

[bergeron]

I dont really know. Trying to make minimal changes when hotfixing things. The decimal check is the only bit that changed recently.

[bergeron]

its true that balance is a string in every place i can reproduce though

[metamaskbot]

Builds ready [40d7d3f]

• builds: chrome, firefox
• builds (beta): chrome
• builds (flask): chrome, firefox
• builds (MMI): chrome, firefox
• builds (test): chrome, firefox
• builds (test-flask): chrome, firefox
• build viz: Build System
• mv3: Background Module Init Stats
• mv3: UI Init Stats
• mv3: Module Load Stats
• mv3: Bundle Size Stats
• mv2: E2e Actions Stats
• code coverage: Report
• storybook: Storybook
• typescript migration: Dashboard
• all artifacts
• bundle viz:

  • background: 0, 1, 2, 3, 4, 5, 6
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Page Load Metrics (2081 ± 74 ms)

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Bundle size diffs [🚀 Bundle size reduced!]

• background: 0 Bytes (0.00%)
• ui: 0 Bytes (0.00%)
• common: -5 Bytes (-0.00%)