Fix svg image export

lib/export/export_collections.rb

@@ -151,8 +151,8 @@ module Export
         fetch_literals(sample)
 
         # collect the sample_svg_file and molecule_svg_file
-        @images << File.join('images', 'samples', sample.sample_svg_file)
-        @images << File.join('images', 'molecules', sample.molecule.molecule_svg_file)
+        fetch_image('samples', sample.sample_svg_file)
+        fetch_image('molecules', sample.molecule.molecule_svg_file)
       end
     end
 
@@ -187,7 +187,7 @@ module Export
         fetch_literals(reaction)
 
         # collect the reaction_svg_file
-        @images << File.join('images', 'reactions', reaction.reaction_svg_file)
+        fetch_image('reactions', reaction.reaction_svg_file)
       end
     end
 
@@ -255,7 +255,7 @@ module Export
         fetch_literals(research_plan)
 
         # collect the svg_file
-        @images << File.join('images', 'research_plans', research_plan.svg_file)
+        fetch_image('research_plans', research_plan.svg_file)
       end
     end
 
@@ -363,6 +363,14 @@ module Export
       end
     end
 
+    def fetch_image(image_path, image_file_name)
+      unless image_file_name.nil? or image_file_name.empty?
+        if File.exist?(File.join('public', 'images', image_path, image_file_name))
+          @images << File.join('images', image_path, image_file_name)
+        end
+      end
+    end
+
     def uuid(type, id)
       unless id.nil?
         # create an empty hash for the type if it does not exist yet