[BUG] No warning when opening file without permission.

[filiera]

When attempting to open a file that the user does not have permission to access, the Editor opens an empty file, but does not display any warning or error message. This behavior can be confusing because it provides no feedback to the user about why the file cannot be opened.

Steps to Reproduce:
Open the Editor in Cosmic Desktop.
Attempt to open a file that you do not have permission to access.

Expected Behavior:
The system should display a warning or error message informing the user that they do not have permission to access the file.

Actual Behavior:
The Editor opens an empty file, but no warning or message is shown.

Cosmic-edit version:

cosmic-edit:
  Installed: 0.1.0~1733263746~24.04~86bcadb
  Candidate: 0.1.0~1733263746~24.04~86bcadb
  Version table:
 *** 0.1.0~1733263746~24.04~86bcadb 1002
       1001 http://apt.pop-os.org/release noble/main amd64 Packages
       1002 http://apt.pop-os.org/staging/master noble/main amd64 Packages
        100 /var/lib/dpkg/status