Quando tento adicionar um produto ao meu carrinho esse erro aparece, pelo o que entendi o erro está no método precoPara, não sou muito bom com lambdas, fiz o curso mas não por completo, segue meu método:

public BigDecimal precoPara(TipoPreco tipoPreco) {
        return precos.stream().filter(preco -> preco.getTipo().equals(tipoPreco)).findFirst().get().getValor();
    }

Segue o stack do erro:

java.lang.Error: Unresolved compilation problem: 
    The method getValor() is undefined for the type Optional<Preco>

    br.com.casadocodigo.loja.models.Produto.precoPara(Produto.java:117)
    br.com.casadocodigo.loja.models.CarrinhoItem.getPreco(CarrinhoItem.java:16)
    br.com.casadocodigo.loja.models.CarrinhoItem.getTotal(CarrinhoItem.java:64)
    br.com.casadocodigo.loja.models.CarrinhoCompras.getTotal(CarrinhoCompras.java:42)
    br.com.casadocodigo.loja.models.CarrinhoCompras.getTotal(CarrinhoCompras.java:48)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    java.lang.reflect.Method.invoke(Unknown Source)
    javax.el.BeanELResolver.getValue(BeanELResolver.java:97)
    org.apache.jasper.el.JasperELResolver.getValue(JasperELResolver.java:110)
    org.apache.el.parser.AstValue.getValue(AstValue.java:169)
    org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:190)
    org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:943)
    org.apache.jsp.WEB_002dINF.views.carrinho.itens_jsp._jspService(itens_jsp.java:246)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:168)
    org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:303)
    org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1286)
    org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1041)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:984)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
Note The full stack trace of the root cause is available in the server logs.