mercurial/statprof.py

--- a/mercurial/statprof.py	Wed Jan 18 23:43:41 2017 -0500
+++ b/mercurial/statprof.py	Wed Jan 18 22:45:07 2017 -0800
@@ -800,6 +800,10 @@
         else:
             assert False, "unhandled option %s" % o
 
+    if not path:
+        print('must specify --file to load')
+        return 1
+
     load_data(path=path)
 
     display(**displayargs)