🐞 fix(getValidateError): treat an empty message array from validate as valid - #13937

Proposed Changes

ValidateResult allows a validate function to return Message[], and getValidateError treats an array of strings as a failure. The check was Array.isArray(result) && result.every(isString), and [].every(...) is always true, so an empty array is also reported as an error, with an empty message.

An empty array is what you naturally get when messages are collected with filter/map:

register('password', {
  validate: {
    rules: (value) =>
      [value.length < 8 && 'too short', !/\d/.test(value) && 'needs a digit'].filter(Boolean),
  },
});

With a valid value the rule returns [], yet errors.password is { type: 'rules', message: '' }, isValid stays false, and submit is blocked with no visible message.

This change only treats the array as an error when it is non-empty. Non-empty arrays behave exactly as before.

No existing issue covers this.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works (getValidateError.test.ts and validateField.test.tsx; both fail before the change)
• New and existing tests pass locally with my changes (jest, pnpm type, pnpm test:type, pnpm lint)