Merge branch 'krille/fix-remove-avatar' into 'main'

fix: Ability to remove avatar from room and account

Closes #223

See merge request famedly/company/frontend/famedlysdk!906

lib/src/client.dart

@@ -821,13 +821,16 @@ class Client extends MatrixApi {
     }
   }
 
-  /// Uploads a new user avatar for this user.
-  Future<void> setAvatar(MatrixFile file) async {
-    final uploadResp = await uploadContent(
-      file.bytes,
-      filename: file.name,
-      contentType: file.mimeType,
-    );
+  /// Uploads a new user avatar for this user. Leave file null to remove the
+  /// current avatar.
+  Future<void> setAvatar(MatrixFile? file) async {
+    final uploadResp = file == null
+        ? null
+        : await uploadContent(
+            file.bytes,
+            filename: file.name,
+            contentType: file.mimeType,
+          );
     await setAvatarUrl(userID!, uploadResp);
     return;
   }

lib/src/room.dart

@@ -1356,15 +1356,18 @@ class Room {
   }
 
   /// Uploads a new user avatar for this room. Returns the event ID of the new
-  /// m.room.avatar event.
-  Future<String> setAvatar(MatrixFile file) async {
-    final uploadResp =
-        await client.uploadContent(file.bytes, filename: file.name);
+  /// m.room.avatar event. Leave empty to remove the current avatar.
+  Future<String> setAvatar(MatrixFile? file) async {
+    final uploadResp = file == null
+        ? null
+        : await client.uploadContent(file.bytes, filename: file.name);
     return await client.setRoomStateWithKey(
       id,
       EventTypes.RoomAvatar,
       '',
-      {'url': uploadResp.toString()},
+      {
+        if (uploadResp != null) 'url': uploadResp.toString(),
+      },
     );
   }