Change add_letter error to a redirect

app/routes.py

@@ -167,7 +167,7 @@ def add_letter() -> Response:
 
     existing_letter_count = len(db.get_user_letters(user.id))
     if user.in_free_tier() and existing_letter_count >= FREE_TIER_TEMPLATES:
-        return render_index(error=f'A maximum of {FREE_TIER_TEMPLATES} templates are available to each user.')
+        return redirect('/?error=template_limit')
     new_letter_name = f'Letter{existing_letter_count + 1}'
     default_form_json = jsonify(CLForm().to_cl_data()).get_data(True)
     db.add_letter(user.id, new_letter_name, default_form_json)
@@ -194,6 +194,9 @@ def index_get() -> Response:
 
     form.letterName.data = 1
     selected_letter = request.args.get('letter_name')
+    error = None
+    if request.args.get('error') == 'template_limit':
+        error = f'A maximum of {FREE_TIER_TEMPLATES} templates are available to each user.'
 
     if selected_letter:
         for i, letter in enumerate(letters):
@@ -216,7 +219,7 @@ def index_get() -> Response:
     form.skillTypes.data = data['skillTypes']
     form.username.data = data['username']
 
-    return render_index(form=form)
+    return render_index(form=form, error=error)
 
 
 @writing_blueprint.route('/reset', methods=['POST', 'GET'])

app/templates/base.jinja2

@@ -59,7 +59,9 @@
 {% else %}
   <div class="user logged-out">
     <form action="/create_account">
-      <div class="black-white-button" style="font-family: 'BarlowMedium'; margin-right: 1em; padding: 0.4em 1em;" onclick="showModal(false, 'Create your account')">Create account</div>
+      <div class="black-white-button" style="font-family: 'BarlowMedium'; margin-right: 1em; padding: 0.4em 1em;" onclick="showModal(false, 'Create your account')">
+          Create account
+      </div>
       <div class="white-black-button" style="margin: 0; padding: 0.4em 1em;" onclick="showModal(true, 'Login now')">Log in</div>
     </form>
   </div>