fix accessing defaultdict

Author: amCap1712

authlib/oauth2/rfc6749/grants/base.py

@@ -147,7 +147,7 @@ def validate_no_multiple_request_parameter(request: OAuth2Request):
         datalist = request.datalist
         parameters = ["response_type", "client_id", "redirect_uri", "scope", "state"]
         for param in parameters:
-            if len(datalist[param]) > 1:
+            if len(datalist.get(param, [])) > 1:
                 raise InvalidRequestError(f'Multiple "{param}" in request.', state=request.state)
 
     def validate_consent_request(self):

authlib/oauth2/rfc7636/challenge.py

@@ -77,7 +77,7 @@ def validate_code_challenge(self, grant):
         if not challenge:
             raise InvalidRequestError('Missing "code_challenge"')
 
-        if len(request.datalist.get('code_challenge')) > 1:
+        if len(request.datalist.get('code_challenge', [])) > 1:
             raise InvalidRequestError('Multiple "code_challenge" in request.')
 
         if not CODE_CHALLENGE_PATTERN.match(challenge):
@@ -86,7 +86,7 @@ def validate_code_challenge(self, grant):
         if method and method not in self.SUPPORTED_CODE_CHALLENGE_METHOD:
             raise InvalidRequestError('Unsupported "code_challenge_method"')
 
-        if len(request.datalist.get('code_challenge_method')) > 1:
+        if len(request.datalist.get('code_challenge_method', [])) > 1:
             raise InvalidRequestError('Multiple "code_challenge_method" in request.')
 
     def validate_code_verifier(self, grant):