From https://github.com/openjdk/jdk/pull/12372#discussion_r1094348012

For a block tag:

    error: no tag name after '@'
         @/
          ^
For an inline tag:

    error: no tag name after '@'
         {@/
          ^
(FWIW, @jonathan-gibbons, note that the caret positions differ: the former points to / while the latter points to @. )