Make FormDataEntryValue type safe by checking of type string

[orangemug]

How to review this PR

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• Check component hierarchy is followed correctly
• Check the design Heuristics have been followed
• Check naming conventions have been applied
• Check for these gotchyas:
  • Missing exports for Oak components
  • Accidental export of Internal components
  • Snapshots of unexpected components have been modified
  • Circular dependencies
  • Code duplication (via not using base components)
  • Non-functional storybook for this or related components
  • Sensitve files changed eg. atoms, or style tokens
  • Relative imports
  • Default exports

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Make FormDataEntryValue type safe by checking of type string

Note that FormDataEntryValue can be either string or File, see https://bun.com/reference/bun/FormDataEntryValue

Fixes

• https://sonarcloud.io/project/issues?open=AZgxmoaQBoQMKbyNldXn&id=oaknational_oak-components
• https://sonarcloud.io/project/issues?open=AZgxmoaQBoQMKbyNldXo&id=oaknational_oak-components

Link to the design doc

None

A link to the component in the deployment preview

https://oak-components-storybook-git-fix-make-formdataentryvalue-504ff4.vercel.thenational.academy/

Testing instructions

ACs

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Project	Deployment	Actions	Updated (UTC)
oak-components-storybook	Ready	Preview, Comment	Feb 3, 2026 4:31pm

[sonarqubecloud]

Quality Gate failed

Failed conditions
75.0% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud