Hi
js error fixed, plugin updated
new version available now 1.3.56
but this is not due to an js error
after adding the marker you clicked button ‘Get the Marker’ ?
http://prntscr.com/q96fja
see doc http://locateandfilter.monothemes.com/docs/locateandfilter-wp-plugin/add-markers/
p. 3.3
http://prntscr.com/q96g01
Set access to a folder wp-content/plugins/thethe-image-slider/cache 777