It is helpful for one's own mental health to Assume Positive Intent when context is missing from messages. If it is really bad news that the other party wants to discuss, there is nothing you can do about it. You might as well deal with it during/after the discussion. If it is a benign discussion, all your anxiety would have been pointless anyway.
The corollary is that if you are sending a message, it just takes a few additional words to provide context (don't be cryptic; don't write a Tolstoy novel). That saves time on both sides. It preps the recipient to come prepared with information for the discussion and hopefully makes the discussion short and productive.