Minor unrelated fixes

src/core/collection/album.rs

@@ -1,7 +1,4 @@
-use std::{
+use std::mem;
-    fmt::{self, Display},
-    mem,
-};
 
 use crate::core::collection::{
     merge::{Merge, MergeName, MergeSorted},
@@ -332,12 +329,6 @@ impl AlbumId {
     }
 }
 
-impl Display for AlbumId {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}", self.title)
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use crate::core::testmod::FULL_COLLECTION;

src/core/collection/merge.rs

@@ -91,7 +91,7 @@ pub struct MergeCollections<T, IT> {
 
 impl<T, IT> MergeCollections<T, IT>
 where
-    T: MergeName + Merge + Ord,
+    T: MergeName + Merge,
     IT: IntoIterator<Item = (String, Vec<T>)>,
 {
     pub fn merge_by_name(primary_items: &mut Vec<T>, secondary: IT) {
@@ -102,7 +102,7 @@ where
                     assert_eq!(secondary_items.len(), 1);
                     primary_item.merge_in_place(secondary_items.pop().unwrap());
                 }
-                None => primary_items.append(&mut secondary_items),
+                None => primary_items.extend(secondary_items),
             }
         }
     }

src/core/musichoard/base.rs

@@ -110,7 +110,7 @@ impl<Database, Library> IMusicHoardBasePrivate for MusicHoard<Database, Library>
         Self::get_album_mut(artist, album_id).ok_or_else(|| {
             Error::CollectionError(format!(
                 "album '{}' does not belong to the artist",
-                album_id
+                album_id.title
             ))
         })
     }