fix header

app.py

@@ -92,13 +92,14 @@ def process(file_name, embed_html_all):
         num_results = 0
         header = False
         for top in tops:
-            if not header:
-                writer.writerow(list(top.keys()))
             if num_results > max_output:
                 break
 
             file = os.path.splitext(os.path.basename(top))[0]
             if file in dict_catalog:
+                if not header:
+                    writer.writerow(list(dict_catalog[file].keys()))
+                    header = True
                 writer.writerow(dict_catalog[file].values())
             else:
                 writer.writerow([file, "no metadata provided"])