Accept missing metadata on attachments

Akkoma/Pleroma (and Friendica until recently) aren't providing attachment meta information like width or height.

Because Mastodon app enforced those fields to be present, attachments would be filtered out.

This commit change the behaviour of Mastodon.Entity.Status.mastodonAttachments by allowing those values to be missing and use default values instead.

MastodonSDK/Sources/MastodonCore/Extension/CoreDataStack/Status+Property.swift

@@ -51,14 +51,28 @@ extension Mastodon.Entity.Status {
         guard let mediaAttachments = mediaAttachments else { return [] }
         
         let attachments = mediaAttachments.compactMap { media -> MastodonAttachment? in
-            guard let kind = media.attachmentKind,
+            guard let kind = media.attachmentKind
-                  let meta = media.meta,
-                  let original = meta.original,
-                  let width = original.width,       // audio has width/height
-                  let height = original.height
             else { return nil }
 
-            let durationMS: Int? = original.duration.flatMap { Int($0 * 1000) }
+            let width: Int;
+            let height: Int;
+            let durationMS: Int?;
+
+            if let meta = media.meta,
+               let original = meta.original,
+               let originalWidth = original.width,
+               let originalHeight = original.height {
+                width = originalWidth;              // audio has width/height
+                height = originalHeight;
+                durationMS = original.duration.flatMap { Int($0 * 1000) }
+            }
+            else {
+                // In case metadata field is missing, use default values.
+                width = 32;
+                height = 32;
+                durationMS = nil;
+            }
+
             return MastodonAttachment(
                 id: media.id,
                 kind: kind,