fix: "today" statistics are not displayed in chart view

[mobiusy]

Summary

Fixes #13105

dify/web/app/(commonLayout)/app/(appDetailLayout)/[appId]/overview/chartView.tsx

Line 56 in abe5aca

const value = TIME_PERIOD_MAPPING[id]?.value || '-1'

Previous:

const value = TIME_PERIOD_MAPPING[id]?.value || '-1'

If TIME_PERIOD_MAPPING[id]?.value is 0, value will be "-1", this is unexpected.
Use nullish coalescing operator for default value in chart view

Current:

const value = TIME_PERIOD_MAPPING[id]?.value ?? '-1'

Screenshots

N/A

Checklist

Important

Please review the checklist below before submitting your pull request.

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods