(GH-674) Fix empty icon now showing
(GH-674) Fix empty icon now showing

If the IconUrl is null or empty, show the empty icon, rather than only
if it is null.

gep13/ChocolateyGUI,gep13/ChocolateyGUI,gep13/ChocolateyGUI,chocolatey/ChocolateyGUI,chocolatey/ChocolateyGUI,gep13/ChocolateyGUI,chocolatey/ChocolateyGUI,chocolatey/ChocolateyGUI,gep13/ChocolateyGUI,chocolatey/ChocolateyGUI