Redirect on invalid UTF-8 in /p/

Previously, uploading a paste with invalid UTF-8 and then viewing it
with the pretty URL would cause a panic.
With this change, it simply redirects to the raw URL.

src/routes/pretty_retrieve.rs

@@ -1,17 +1,28 @@
+use rocket::response::Redirect;
 use rocket_dyn_templates::Template;
 
 use std::collections::HashMap;
+use std::io::ErrorKind::InvalidData;
 use std::path::Path;
 
 use crate::get_upload_dir;
+use crate::models::maybe_redirect::MaybeRedirect;
 use crate::models::paste_id::PasteId;
 use crate::models::pretty::get_pretty_body;
 
 #[get("/p/<id>", rank = 2)]
-pub async fn pretty_retrieve(id: PasteId<'_>) -> Option<Template> {
+pub async fn pretty_retrieve(id: PasteId<'_>) -> Option<MaybeRedirect> {
     let filepath = Path::new(&get_upload_dir()).join(format!("{id}", id = id));
 
-    let contents = get_pretty_body(&filepath, &String::from("txt"));
+    let contents = match get_pretty_body(&filepath, &String::from("txt")) {
+        Ok(v) => v,
+        Err(e) if e.kind() == InvalidData => {
+            return Some(Redirect::to(format!("/{}", id)).into());
+        }
+        _ => {
+            return None;
+        }
+    };
 
     let mut map = HashMap::new();
     map.insert("title", id.to_string());
@@ -19,7 +30,7 @@ pub async fn pretty_retrieve(id: PasteId<'_>) -> Option<Template> {
     let rendered = Template::render("pretty.html", &map);
 
     match tree_magic::match_filepath("text/plain", &filepath) {
-        true => Some(rendered),
+        true => Some(rendered.into()),
         false => None,
     }
 }