Turn empty images into error. Closes #8

src/banner_changer.rs

@@ -218,6 +218,9 @@ impl ChangerError {
                     info!("Letting owner={guild_owner} of guild={guild_id} know about the missing banner feature");
 
                     dm_user(&ctx, guild_owner, &"Server has lost the required boost level. Stopping schedule. You can restart the bot after gaining the required boost level.").await?;
+                },
+                SetBannerError::ImageIsEmpty => {
+                    warn!("guild_id={guild_id} with album={} has downloaded an image with 0 bytes", self.schedule.album());
                 }
             },
             err => {

src/guild_id_ext.rs

@@ -23,6 +23,8 @@ pub enum SetBannerError {
     CouldNotDeterminFileExtension,
     #[error("Missing 'banner' feature")]
     MissingBannerFeature,
+    #[error("Image is empty")]
+    ImageIsEmpty
 }
 
 #[async_trait]
@@ -88,10 +90,8 @@ impl RandomBanner for GuildId {
         let amount_of_bytes = image_bytes.len();
         debug!("Amount of image bytes downloaded: {}", amount_of_bytes);
 
-        // @todo proper error handling for this case.
-        // for now an early return will be enough
         if amount_of_bytes == 0 {
-            return Ok(());
+            return Err(SetBannerError::ImageIsEmpty);
         }
 
         let b64 = base64::engine::general_purpose::STANDARD.encode(&image_bytes);