Fix “Invalid media attachments” crash.

// FREEBIE

Signal/src/Models/TSMessageAdapaters/TSAnimatedAdapter.m

@@ -103,8 +103,7 @@ NS_ASSUME_NONNULL_BEGIN
         NSData *fileData = [NSData dataWithContentsOfURL:[self.attachment mediaURL]];
         if (!fileData) {
             DDLogError(@"%@ Could not load image: %@", [self tag], [self.attachment mediaURL]);
-            OWSAssert(0);
-            return nil;
+            return [UIView new];
         }
         FLAnimatedImage *animatedGif = [FLAnimatedImage animatedImageWithGIFData:fileData];
         FLAnimatedImageView *imageView = [[FLAnimatedImageView alloc] init];

Signal/src/Models/TSMessageAdapaters/TSPhotoAdapter.m

@@ -75,8 +75,7 @@ NS_ASSUME_NONNULL_BEGIN
         UIImage *image = self.attachment.image;
         if (!image) {
             DDLogError(@"%@ Could not load image: %@", [self tag], [self.attachment mediaURL]);
-            OWSAssert(0);
-            return nil;
+            return [UIView new];
         }
         CGSize size             = [self mediaViewDisplaySize];
         UIImageView *imageView = [[UIImageView alloc] initWithImage:image];

Signal/src/Models/TSMessageAdapaters/TSVideoAttachmentAdapter.m

@@ -227,8 +227,7 @@ NS_ASSUME_NONNULL_BEGIN
     UIImage *image = self.attachment.image;
     if (!image) {
         DDLogError(@"%@ Could not load image: %@", [self tag], [self.attachment mediaURL]);
-        OWSAssert(0);
-        return nil;
+        return [UIView new];
     }
     UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
     imageView.contentMode = UIViewContentModeScaleAspectFill;