On why you cannot see the error on a GET request, that is because content in the “body” is not part of a GET request, API’s don’t generally consider or validate the body of a GET request as the endpoint is built for providing a response and not processing or accepting data whereas a POST endpoint is built for accepting “body” data, processing data and sending back a response.
With regards to the error, its possible you have copied "(Double Quotes) from a text instead of ", I would suggest you manually enter the double quotes between the text again and test it out.