minor fix regarding last commit

lib/techniques/error/use.py

@@ -78,7 +78,8 @@ def __oneShotErrorUse(expression, field):
                 if threadData.lastRedirectMsg and threadData.lastRedirectMsg[0] == \
                 threadData.lastRequestUID else None, re.DOTALL | re.IGNORECASE)
 
-        output = getUnicode(output, kb.pageEncoding)
+        if output:
+            output = getUnicode(output, kb.pageEncoding)
 
         if isinstance(output, basestring):
             output = htmlunescape(output).replace("<br>", "\n")

lib/techniques/inband/union/use.py

@@ -65,7 +65,8 @@ def __oneShotUnionUse(expression, unpack=True):
             or extractRegexResult(check, removeReflectiveValues(listToStrValue(headers.headers \
             if headers else None), payload), re.DOTALL | re.IGNORECASE)
 
-    output = getUnicode(output, kb.pageEncoding)
+    if output:
+        output = getUnicode(output, kb.pageEncoding)
 
     return output