Error handling updates

src/fs.rs

     match read_to_string(&path).await {
         Ok(c) => Ok(c),
         Err(_) => Err(Error::new(
-            ErrorKind::Other,
-            format!("Error reading post {:?}", &path),
+            ErrorKind::NotFound,
+            format!(
+                "Can't find post with the id '{}'",
+                path.file_stem().unwrap().to_str().unwrap()
+            ),
         )),
     }
 }

src/main.rs

     let mut app = tide::new();
 
     app.with(After(|mut res: Response| async {
-        if let Some(err) = res.downcast_error::<async_std::io::Error>() {
-            let mut context = Context::new();
-            context.insert("error", &err.to_string());
-            res.set_body(render("error.html", &context)?);
-            res.set_status(StatusCode::InternalServerError);
-        }
+        let mut context = Context::new();
+
+        match res.downcast_error::<async_std::io::Error>() {
+            Some(e) => {
+                context.insert("error", &e.to_string());
+                let status = if let ErrorKind::NotFound = e.kind() {
+                    StatusCode::NotFound
+                } else {
+                    StatusCode::InternalServerError
+                };
+                res.set_body(render("error.html", &context)?);
+                res.set_status(status);
+            }
+            None => match res.status() {
+                StatusCode::NotFound => {
+                    context.insert("error", "Page not found");
+                    res.set_body(render("error.html", &context)?);
+                }
+                _ => {}
+            },
+        };
 
         Ok(res)
     }));