feat(qrgen): deny empty string; fix Submit button

app/qrwebform.py

@@ -2,7 +2,8 @@
 
 from flask import Flask, render_template, flash, request
 from flask_wtf import FlaskForm
-from wtforms import Form, TextField, BooleanField
+from wtforms import Form, BooleanField, SubmitField, TextField
+from wtforms.validators import DataRequired
 import os
 
 DEBUG = False
@@ -11,8 +12,9 @@ app.config.from_object(__name__)
 app.config['SECRET_KEY'] = os.urandom(40)
 
 class QRForm(FlaskForm):
-    user_data = TextField("Dane:")
+    user_data = TextField("Dane:", validators=[DataRequired()])
     trim_spaces = BooleanField("Usuń spacje", default=True)
+    submit = SubmitField("Generuj")
 
     @app.route("/", methods=["GET", "POST"])
     def main():