Snowflake Response Translator - Uncaught SyntaxError: "[object Object]" is not valid JSON

My external function looks like this:

create or replace external function test(value string)
    returns variant
    RETURNS NULL ON NULL INPUT
    api_integration = my_api
    response_translator = TEST_SNOWFLAKE.PUBLIC.response_translator
    as 'https://abc'
;

My response translator:

CREATE OR REPLACE FUNCTION response_translator(EVENT OBJECT)
RETURNS OBJECT
LANGUAGE JAVASCRIPT AS
'
const parsedJson = JSON.parse(EVENT.body);
const parsedJsonString = JSON.stringify(parsedJson);
const modifiedJson = {
  "data": [
    [0, parsedJsonString]
  ]
};
return modifiedJson;
';

When using this test:

select response_translator(parse_json('  {"body": "{\\"error\\":{\\"grpc_code\\":5,\\"http_code\\":404,\\"message\\":\\"Resource not found\\",\\"http_status\\":\\"Not Found\\"}}"
}'));

the response translator works fine.

However, when triggering the external function with:

select test('abc123');

which has the following response as seen in the AWS Lambda logs:

{
  "statusCode": 200,
  "headers": null,
  "multiValueHeaders": null,
  "body": "{\"error\":{\"grpc_code\":5,\"http_code\":404,\"message\":\"Resource not found\",\"http_status\":\"Not Found\"}}"
}

I get this error in my snowflake console:

JavaScript execution error: Uncaught SyntaxError: "[object Object]" is not valid JSON in RESPONSE_TRANSLATOR at '[object Object]' position 1

Why am I getting this error?

This response translator got it working:

CREATE OR REPLACE FUNCTION response_translator(EVENT OBJECT)
RETURNS OBJECT
LANGUAGE JAVASCRIPT AS
'
if (EVENT.body.error!=null){
const modifiedJson = {"body":{
  "data": [
    [0, EVENT.body]
  ]
}};
return modifiedJson;}
';