null image measurements at contents change

image_list.py

@@ -6,6 +6,7 @@ import re
 import sqlite3
 import subprocess
 import hashlib
+import traceback
 from argparse import ArgumentParser 
 
 SQLFILE='list_of_images.sqlite'
@@ -129,6 +130,7 @@ def add_recurse(options):
                             add_single(conn,filename,change=False,minsize=options.minsize)
                         except:
                             print('error adding file: '+filename)
+                            traceback.print_exc(file=sys.stdout)
                             sys.exit(1)
                 else:
                     if options.changed: