Don't query Google with empty string.

lib/geocoder.rb

@@ -213,6 +213,7 @@ module Geocoder
   # Returns array [lat,lon] if found, nil if not found or if network error.
   #
   def self.fetch_coordinates(query)
+    return nil if query.blank?
     return nil unless doc = self.search(query)
     
     # make sure search found a result