Error when given an invalid image file

PluralKit.Bot/Errors.cs

@@ -34,6 +34,7 @@ namespace PluralKit.Bot {
         public static PKError AvatarFileSizeLimit(long size) => new PKError($"File size too large ({size.Bytes().ToString("#.#")} > {Limits.AvatarFileSizeLimit.Bytes().ToString("#.#")}), try shrinking or compressing the image.");
         public static PKError AvatarNotAnImage(string mimeType) => new PKError($"The given link does not point to an image{(mimeType != null ? $" ({mimeType.SanitizeMentions()})" : "")}. Make sure you're using a direct link (ending in .jpg, .png, .gif).");
         public static PKError AvatarDimensionsTooLarge(int width, int height) => new PKError($"Image too large ({width}x{height} > {Limits.AvatarDimensionLimit}x{Limits.AvatarDimensionLimit}), try resizing the image.");
+        public static PKError AvatarInvalid => new PKError($"Could not read image file - perhaps it's corrupted or the wrong format. Try a different image.");
         public static PKError UserHasNoAvatar => new PKError("The given user has no avatar set.");
         public static PKError InvalidUrl(string url) => new PKError($"The given URL is invalid.");
         

PluralKit.Bot/Utils.cs

@@ -62,6 +62,7 @@ namespace PluralKit.Bot
                 // Parse the image header in a worker
                 var stream = await response.Content.ReadAsStreamAsync();
                 var image = await Task.Run(() => Image.Identify(stream));
+                if (image == null) throw Errors.AvatarInvalid;
                 if (image.Width > Limits.AvatarDimensionLimit || image.Height > Limits.AvatarDimensionLimit) // Check image size
                     throw Errors.AvatarDimensionsTooLarge(image.Width, image.Height);
             }