Regression from
https://github.com/eclipse-jdt/eclipse.jdt.core/pull/4451 &
https://github.com/eclipse-jdt/eclipse.jdt.core/pull/4302.

If Java Editor interrupts hover computation, nothing should be reported,
as it is expected. After changes above two errors are reported into the
log (with same stack).

Fixes https://github.com/eclipse-jdt/eclipse.jdt.ui/issues/2769