[rdf_converter.py] Add subclass_path Check Again

Author: fschrader1992

odml/tools/rdf_converter.py

@@ -46,12 +46,13 @@ def __init__(self, odml_documents):
         subclass_path = os.path.join(dirname(dirname(dirname(abspath(__file__)))),
                          'doc', 'section_subclasses.yaml')
 
-        with open(subclass_path, "r") as f:
-            try:
-                self.section_subclasses = yaml.load(f)
-            except yaml.parser.ParserError as err:
-                print(err)
-                return
+        if os.path.isfile(subclass_path):
+            with open(subclass_path, "r") as f:
+                try:
+                    self.section_subclasses = yaml.load(f)
+                except yaml.parser.ParserError as err:
+                    print(err)
+                    return
 
     def convert_to_rdf(self):
         self.hub_root = URIRef(odmlns.Hub)