fixed #166

ChangeLog

@@ -6,7 +6,8 @@ ChangeLog
   - remove unittest2 requirements for python 2.6 (#156)
   - fixed subprotocol case during header validation (#158)
   - get response status and headers (#160)
-  - fix out-of-memory due to fragmentation when recieving a very large frame #163
+  - fix out-of-memory due to fragmentation when recieving a very large frame(#163)
+  - fix error if the payload data is nothing.(#166)
   - refactoring.
 
 - 0.26.0

websocket/_abnf.py

@@ -98,6 +98,8 @@ class ABNF(object):
         self.rsv3 = rsv3
         self.opcode = opcode
         self.mask = mask
+        if data == None:
+            data = ""
         self.data = data
         self.get_mask_key = os.urandom
 
@@ -204,7 +206,8 @@ class ABNF(object):
 
         data: data to mask/unmask.
         """
-
+        if data == None:
+            data = ""
         if isinstance(mask_key, six.text_type):
             mask_key = six.b(mask_key)