Make sure to initialize lookup table even if LookupType is set.

add_glyphs.py

@@ -259,8 +259,8 @@ def get_gsub_ligature_lookup(font):
     assert lookup.LookupFlag == 0
 
     # importXML doesn't fully init GSUB structures, so help it out
-    if not hasattr(lookup, 'LookupType'):
     st = lookup.SubTable[0]
+    if not hasattr(lookup, 'LookupType'):
       assert st.LookupType == 4
       setattr(lookup, 'LookupType', 4)