debug get picture

utilities.py

@@ -151,13 +151,13 @@ def get_sp_picture(sp_dict_list):
         # no picture stored yet for this genus_species
         if genus_species not in sp_picture_dict.keys() \
             or (genus_species in sp_picture_dict.keys()
-                and sp_picture_dict[genus_species] == ""):
+                and sp_picture_dict[genus_species] == None):
 
             if constants.ORG_PARAM_DESC_PICTURE_PATH in sp[constants.ORG_PARAM_DESC].keys() and \
-                    sp[constants.ORG_PARAM_DESC][constants.ORG_PARAM_DESC_PICTURE_PATH] != "":
+                    sp[constants.ORG_PARAM_DESC][constants.ORG_PARAM_DESC_PICTURE_PATH] != None:
                 sp_picture_dict[genus_species] = sp[constants.ORG_PARAM_DESC][constants.ORG_PARAM_DESC_PICTURE_PATH]
             else:
-                sp_picture_dict[genus_species] = ""
+                sp_picture_dict[genus_species] = None
 
         # overwrite stored picture if a picture exists for the main strain
         if (constants.ORG_PARAM_DESC_MAIN_SPECIES in sp[constants.ORG_PARAM_DESC].keys()