Issue #16504: Catch SyntaxErrors raised by tokenizer in IDLE.
diff --git a/Lib/idlelib/EditorWindow.py b/Lib/idlelib/EditorWindow.py
index efd3c54..0a01c9e 100644
--- a/Lib/idlelib/EditorWindow.py
+++ b/Lib/idlelib/EditorWindow.py
@@ -1611,7 +1611,7 @@
         try:
             try:
                 _tokenize.tokenize(self.readline, self.tokeneater)
-            except _tokenize.TokenError:
+            except (_tokenize.TokenError, SyntaxError):
                 # since we cut off the tokenizer early, we can trigger
                 # spurious errors
                 pass