Cs50 Finance Form Error 500 when filled in wrong

I am trying to provide error message when user write a wrong stock name. However, I am getting an internal server error always.

@app.route("/quote", methods=["GET", "POST"])
@login_required
def quote():
"""Get stock quote."""
if request.method == "GET":
    return render_template("quote.html")
    
else:
    x =lookup(request.form.get("symbol"))
    name =x["name"]
    price =x["price"]
    
    #apology message for none value CIKMIYOOOO
    if x["name"] == None:
        return apology("Stock doesn't exist",403)