Added error checker for plugin installation.
Added error checker for plugin installation.

evothings/evothings-viewer,mikaelkindborg/evothings-viewer,mikaelkindborg/evothings-viewer,mikaelkindborg/evothings-viewer,evothings/evothings-viewer,evothings/evothings-viewer,evothings/evothings-viewer,mikaelkindborg/evothings-viewer