Preview of file is not working after execution File Manager Document macro

[petrenkonikita112263]

Environment: XWiki 15.9, Windows 10.

Prerequisites:

• XWiki instance 15.x.
• Latest version of File Manager (Pro).
• Trial license
• At least one uploaded file

Step to reproduce:

1. Navigate into dedicated page.
2. Insert File Manager Document macro via QuickActions or from toolbar menu.
3. Pass the page reference where uploaded file is stored.
4. Check the preview.

Actual result:
The preview function doesn't work on File Manager Document macro, even with unchecked (default state) preview, the result is the same.

Expected result:
Inside the cell, not even information about a file is displayed, but the viewer macro allows you to see the file.

Note: if edit the reference {{filemanagerdoc page="FileManager.test image\.jpg" preview="true"/}} and remove \ than the empty cell will be displayed.

[petrenkonikita112263]

With a new version of File Manager (Pro) 2.8, it is still the same; however I started to think this may not be the issue and the intended way if the user tried to use File Manager Document macro, and if a user wants to see file that user needs click on URL that will redirect to page with this file. But store documentation lacks information about its usage and result.

[petrenkonikita112263]

I tested LTS XWiki version 16.10.5 using File Manager (Pro) 2.8.1. I can't save an XWiki page using the macro mentioned - I get an infinite spinner

In console logs error concerning "FormData" that requires JS object.

actionButtons.js:261 
 Uncaught TypeError: Failed to construct 'FormData': parameter 1 is not of type 'HTMLFormElement'.
    at klass.getFormData (actionButtons.js:261:24)
    at klass.onSave (actionButtons.js:324:27)
    at HTMLDocument.<anonymous> (prototype.js?r=1:417:23)
    at HTMLDocument.<anonymous> (prototype.js?r=1:7282:15)
    at fireEvent_DOM (prototype.js?r=1:7141:13)
    at fire (prototype.js?r=1:7130:17)
    at k (eventsBridge.js:61:26)
    at HTMLInputElement._methodized [as fire] (prototype.js?r=1:456:23)
    at klass.notify (actionButtons.js:201:43)
    at S.XWiki.actionButtons.EditActions.notify (InplaceEditing?langu…cVersion=1.1:20:490)
```