One built-in feature of the Zotero Connector web browser plugin is proxy redirection. This can facilitate easier login processes on some websites, but may cause an error message to appear in your web browser when accessing library databases and resources.
This problem can, thankfully, be easily resolved.
When this pop-up is visible, select Proxy Settings.
After this, deselect "Enable proxy redirection" from the Proxies selection on the Zotero Connector settings menu. This will deselect all proxy redirection options in the plugin, and should prevent the pop-up from appearing on databases accessed through the SMSU library.