42: Target text missing

You used the hash # which marks a target outside an URI or math string. Targets are required to contain at least one printable character, which your target does not. Aneamal marks such as ~ do not count as printable characters in this context.

Solution

Set a target that contains at least one printable character:

Look! What a fabulous #target!
Here is yet #`another target`.

If you did not mean to set a target but want to use the hash # literally, you can prepend a backslash: \#