Downloader: Change cache_image function to return Result<T, DownlaoderError> instead of Option<T>.

hammond-gtk/src/app.rs

@@ -122,9 +122,9 @@ impl App {
             match receiver.recv_timeout(Duration::from_millis(10)) {
                 Ok(Action::UpdateSources(source)) => {
                     if let Some(s) = source {
-                        utils::refresh_feed(Some(vec![s]), sender.clone())
+                        utils::refresh_feed(Some(vec![s]), sender.clone());
                     } else {
-                        utils::refresh_feed(None, sender.clone())
+                        utils::refresh_feed(None, sender.clone());
                     }
                 }
                 Ok(Action::RefreshAllViews) => content.update(),

hammond-gtk/src/utils.rs

@@ -1,5 +1,6 @@
 #![cfg_attr(feature = "cargo-clippy", allow(type_complexity))]
 
+use failure::Error;
 use gdk_pixbuf::Pixbuf;
 use send_cell::SendCell;
 
@@ -82,7 +83,7 @@ pub fn get_pixbuf_from_path(pd: &PodcastCoverQuery, size: u32) -> Option<Pixbuf>
         }
     }
 
-    let img_path = downloader::cache_image(pd)?;
+    let img_path = downloader::cache_image(pd).ok()?;
     let px = Pixbuf::new_from_file_at_scale(&img_path, size as i32, size as i32, true).ok();
     if let Some(px) = px {
         let mut hashmap = CACHED_PIXBUFS.write().unwrap();