When package exists in folder Install\Module with an invalid icon path the page "Host > Extension" just show "DNN Error" and you are not able to manage modules.
To reproduce, just put the attached DNNCE_HTML_07.03.02_Install-Broken.zip file in Install\Module and try to access "Host > Extension".
This package contains a manifest file with an invalid icon path ("...").
I will create a pull request with a fix for DotNetNuke.Modules.Admin.Extensions.AvailableExtensions.IconExists()
Verified using attached package in Platform/Content/Enterprise 7.3.3 build 93