### Is there an existing issue for this?

- [X] I have searched the existing issues and read the documentation

### Question

After configuring it  withEnv("DYNAMODB_WRITE_ERROR_PROBABILITY", "1.0") — it is expected to throw dynamo throuput exception , but throwing 500 error - `(Service: DynamoDb, Status Code: 500, Request ID: null, Extended Request ID: null)","operationType":"PutItem","kinesisRecordMetaData":{"recordInsertionDate":"01-01-2021"}}, Response - PutObjectResponse(ETag="5435b0664a1337227d380fbd83ebcc89")

### Anything else?

_No response_
"""Check whether a valid region is provided, and if not then raise an Exception."""
    auth_header = headers.get("Authorization")
    if not auth_header:
        raise Exception('Unable to find "Authorization" header in request')
    replaced = re.sub(r".*Credential=([^,]+),.*", r"\1", auth_header)
    if auth_header == replaced:
        raise Exception('Unable to find "Credential" section in "Authorization" header')
    
    
    parts = replaced.split("/")
    region = parts[2]
    if region not in get_valid_regions():
        raise Exception(f'Invalid region specified in "Authorization" header: "{region}"')
def set_default_region_in_headers(headers, service=None, region=None):
    
    
    if not config.USE_SINGLE_REGION:
        return
    auth_header = headers.get("Authorization")
    region = region or get_region()
    if not auth_header:
        if service:
            headers["Authorization"] = mock_aws_request_headers(service, region_name=region)[
                "Authorization"
            ]
        return
    replaced = re.sub(r"(.*Credential=[^/]+/[^/]+/)([^/])+/", r"\1%s/" % region, auth_header)
    headers["Authorization"] = replaced
def fix_account_id_in_arns(response, colon_delimiter=":", existing=None, replace=None):