fix: file input handler

[DmytroAlipov]

This is a backport from the master branch.

hasFile run only once, it will always be null

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

:exclamation: No coverage uploaded for pull request base (open-release/palm.master@3644172). Click here to learn what that means.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## open-release/palm.master #371 +/- ## ============================================================ Coverage ? 100.00% ============================================================ Files ? 122 Lines ? 1268 Branches ? 249 ============================================================ Hits ? 1268 Misses ? 0 Partials ? 0 ```

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[mphilbrick211]

Hi @openedx/content-aurora! I think this is ready for merge, the master has already been merged.

[cmltaWt0]

Looked through the diff - looks exactly the same as for master. Seems safe to merge. Merging.

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