"Download video" button gets stuck at an infinispinner if room is encrypted and download returns error

[richvdh]

Suppose the media repository is having a bad day, and returning 500 errors; or that the video you are looking for has been removed/was never correctly uploaded.

1. Click the download button on an encrypted video:
   
2. ...

The button turns into an infinispinner, with the (misleading) hover text "Decrypting":

There is an error in the console:

14:30:22.526 Uncaught (in promise) DownloadError: MatrixError: [404] Not found (http://localhost:8008/_matrix/media/v3/download/xps9320.sw1v.org/WyNoQOaWfantxfwmByFbWsIW?allow_redirect=true)
    HTTPError errors.ts:37
    MatrixError errors.ts:66
    parseErrorResponse utils.ts:83
    decryptFile DecryptFile.ts:59
    MediaEventHelper MediaEventHelper.ts:85
    get value LazyValue.ts:48
    DownloadActionButton DownloadActionButton.tsx:70
    node_modules default-vendors-node_modules_matrix-org_react-sdk-module-api_lib_components_Spinner_js-node_m-a1bc8b.js:109768
    node_modules default-vendors-node_modules_matrix-org_react-sdk-module-api_lib_components_Spinner_js-node_m-a1bc8b.js:109768
    React 14
    unstable_runWithPriority scheduler.development.js:468
    React 15
    loadApp init.tsx:108
    start index.ts:244
    ts index.ts:255
    Webpack 5

[richvdh]

See also #27861, which is much the same problem, applied to unencrypted video