title: Hydrapaper will not open - need help interpreting errors
body: <p>I'm running Ubuntu 20.04.3 LTS and until recently, I used Hydrapaper for my dual monitor setup. It's not imperative that I be able to have separate wallpapers but I am being driven kind of mad by the errors I'm seeing when I try to open Hydrapaper from the terminal. This is what I get:</p>
  <pre class="lang-sh prettyprint-override"><code>
  michael@michael-Inspiron-7790-AIO:~$ flatpak run org.gabmus.hydrapaper
  Traceback (most recent call last):
    File &quot;/app/lib/python3.9/site-packages/hydrapaper/__main__.py&quot;, line 206, in do_command_line
      self.do_activate()
    File &quot;/app/lib/python3.9/site-packages/hydrapaper/__main__.py&quot;, line 146, in do_activate
      self.window = HydraPaperAppWindow()
    File &quot;/app/lib/python3.9/site-packages/hydrapaper/app_window.py&quot;, line 44, in __init__
      self.monitors_flowbox = HydraPaperMonitorsFlowbox()
    File &quot;/app/lib/python3.9/site-packages/hydrapaper/monitors_flowbox.py&quot;, line 132, in __init__
      self.populate()
    File &quot;/app/lib/python3.9/site-packages/hydrapaper/monitors_flowbox.py&quot;, line 151, in populate
      HydraPaperMonitorsFlowboxItem(m), -1
    File &quot;/app/lib/python3.9/site-packages/hydrapaper/monitors_flowbox.py&quot;, line 71, in __init__
      self.set_picture()
    File &quot;/app/lib/python3.9/site-packages/hydrapaper/monitors_flowbox.py&quot;, line 94, in set_picture
      pixbuf = GdkPixbuf.Pixbuf.new_from_file_at_scale(
  gi.repository.GLib.GError: gdk-pixbuf-error-quark: Couldn’t recognize the image file format for file “/home/michael/.var/app/org.gabmus.hydrapaper/cache/org.gabmus.hydrapaper/thumbnails//a5debe6ea02641a70325dc008910a85c61765e55906c29dd338e9f63506378a4.png” (3)
  </code></pre>
  <p>And as I said, Hydrapaper won't open. It appears in my topbar for a few seconds then disappears. Can anyone suggest a fix? Thanks in advance.</p>