Use helper render function

src/main.rs

     Ok(posts)
 }
 
+fn render(template: &str, context: &Context) -> Result<Body, tide::Error> {
+    let tera = Tera::new("templates/**/*.html")?;
+    let html = tera.render(template, &context)?;
+    Ok(Body::from_string(html))
+}
+
 #[async_std::main]
 async fn main() -> std::io::Result<()> {
     dotenv::dotenv().ok();
 
     app.with(After(|mut res: Response| async {
         if let Some(err) = res.downcast_error::<async_std::io::Error>() {
-            let tera = Tera::new("templates/**/*.html")?;
             let mut context = Context::new();
             context.insert("error", &err.to_string());
-            let html = tera.render("error.html", &context)?;
-            res.set_body(html);
+            res.set_body(render("error.html", &context)?);
             res.set_status(StatusCode::InternalServerError);
         }
 
     ));
 
     app.at("/").get(|req: tide::Request<()>| async move {
-        let tera = Tera::new("templates/**/*.html")?;
         let posts = read_all_posts().await?;
         let mut context = Context::new();
         context.insert("posts", &posts);
         let logged_in: bool = req.session().get("logged_in").unwrap_or(false);
         context.insert("logged_in", &logged_in);
-        let html = tera.render("index.html", &context)?;
-        Ok(Body::from_string(html))
+        render("index.html", &context)
     });
 
     app.at("/posts")
 
     app.at("/login")
         .get(|mut req: tide::Request<()>| async move {
-            let tera = Tera::new("templates/**/*.html")?;
             let mut context = Context::new();
             let logged_in: bool = req.session().get("logged_in").unwrap_or(false);
             context.insert("logged_in", &logged_in);
                 }
                 None => {}
             }
-            let html = tera.render("login.html", &context)?;
-            Ok(Body::from_string(html))
+            render("login.html", &context)
         })
         .post(|mut req: tide::Request<()>| async move {
             let logged_in: bool = req.session().get("logged_in").unwrap_or(false);