Don't crash in the profile editor when script.db is missing.

CHANGELOG

@@ -1,5 +1,9 @@
 # Nmap Changelog ($Id$); -*-text-*-
 
+o [Zenmap] Fixed a crash that would happen in the profile editor when
+  the script.db file doesn't exist. The bug was reported by Daniel
+  Miller.
+
 o [Zenmap] It is now possible to compare scans having the same name or
   command line. [Jah, David Fifield]
 

zenmap/zenmapCore/ScriptMetadata.py

@@ -417,7 +417,10 @@ def get_script_entries(scripts_dir, nselib_dir):
     """Merge the information obtained so far into one single entry for
     each script and return it."""
     metadata = ScriptMetadata(scripts_dir, nselib_dir)
+    try:
         scriptdb = ScriptDB(os.path.join(scripts_dir, "script.db"))
+    except IOError:
+        return []
     entries = []
     for dbentry in scriptdb.get_entries_list():
         entry = metadata.get_metadata(dbentry["filename"])