[MM-57826] Make sure the original errors are wrapped when AppErrors are returned (#26771)

Co-authored-by: Ibrahim Serdar Acikgoz <serdaracikgoz86@gmail.com>

server/channels/api4/channel.go

@@ -1822,7 +1822,7 @@ func addChannelMember(c *Context, w http.ResponseWriter, r *http.Request) {
 			if v, ok := err.(*model.AppError); ok {
 				c.Err = v
 			} else {
-				c.Err = model.NewAppError("addChannelMember", "api.channel.add_members.error", nil, err.Error(), http.StatusBadRequest)
+				c.Err = model.NewAppError("addChannelMember", "api.channel.add_members.error", nil, "", http.StatusBadRequest).Wrap(err)
 			}
 			return
 		}