Unsaved form data is lost without warning when reopening PDF

 * Xreader version 2.4.4
 * Distribution - Linux Mint 19.3

Issue

A filled-in PDF Form with unsaved entries gets closed (i.e. loses all entered data) with no warning if you re-open the same PDF file, either externally or by selecting the file from the Xreader File menu. Since closing a form with unsaved data brings up the "Save a copy?" dialog, I would expect any similar action which would clear the form data to do the same, allowing me to confirm or cancel that action.

Steps to reproduce

1. Open a PDF file containing a fill-in form.
2. Enter some data into the form (press enter after typing to ensure it gets stored).
3. Press Control+W or select File::Close. Confirm that the dialog "Save a copy" appears. Hit Cancel so the file remains open.

Then either:

4. From the Xreader menu, select File :: 1. to re-open the same file. File gets re-opened with form data cleared without warning.

or

4. Using Nemo, any other file browser, or the command-line, re-open the same PDF file. File gets re-opened with form data cleared without warning.

Expected behaviour

Reopening a PDF file which is already open and has unsaved form data should at least give me a warning and the ability to cancel. I needed to open multiple copies of the same file with different form data so it would be nice for one of the choices of any warning dialog to mean "open the file again from scratch without closing the existing window" although now I know how it works I can replicate that using "save a copy" from the File menu.

No source file, test, or code entry point is named. Start by tracing the File-menu reopen action and the external-file-open path while reproducing the form-data loss; done means reopening a PDF with unsaved form data warns the user and permits cancellation without clearing the existing data.