More elegant error handling

ref-test/app/quiz/views.py

@@ -1,5 +1,6 @@
 from ..forms.quiz import StartQuiz
 from ..models import Entry, Test
+from ..tools.forms import send_errors_to_client
 from ..tools.test import redirect_if_started
 
 from flask import abort, Blueprint, jsonify, redirect, render_template, request, session
@@ -52,8 +53,7 @@ def _start():
                     'id': entry.id
                 }), 200
             return jsonify({'error': 'There was an error processing the user test and/or user codes.'}), 400
-        errors = [*form.test_code.errors, *form.user_code.errors, *form.first_name.errors, *form.surname.errors, *form.email.errors, *form.club.errors]
-        return jsonify({ 'error': errors}), 400
+        return send_errors_to_client(form=form)
     return render_template('/quiz/start_quiz.html', form = form)
 
 @quiz.route('/quiz/')