How to return a JSON in @ExceptionHandler when a resource is not found

Question

How an application which serves resources (.js; .css...) could return JSON entities if an error occurs ?

I wrote a ControllerExceptionHandler according to this blog:

package com.my.rest;

import com.my.rest.errors.ErrorMessage;
import com.my.rest.errors.ErrorMessageFactory;
import com.my.service.errors.NotFoundException;
import com.my.service.errors.ValidationException;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.context.request.WebRequest;
import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;

import static org.springframework.http.HttpStatus.NOT_FOUND;

@ControllerAdvice
@ResponseBody
public class GlobalControllerExceptionHandler extends ResponseEntityExceptionHandler {

    @Autowired
    private ErrorMessageFactory messageFactory;

    @ResponseStatus(NOT_FOUND)
    @ExceptionHandler({NotFoundException.class})
    public ResponseEntity<Object> handleServiceException(RuntimeException e, WebRequest request) {

        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_JSON_UTF8);

        return handleExceptionInternal(e, messageFactory.generateMessage(e), headers, HttpStatus.NOT_FOUND, request);
    }

}

If the request URL is: https://my-server/resources/a.js, but a.js is not found, this ExceptionHandler leads to a HttpMediaTypeNotAcceptableException thrown by AbstractMessageConverterMethodProcessor because ContentNegotiationManager uses a strategy based on the extension .js, and determines that ErrorMessage is not applicable to the media type application/javascript.

My question is: Is there a way to ignore the check of media type to always send JSON error responses so that the client-side error management can parse it ?

Thank you