Conditionally print subsection in Beamer

I have replaced the code snippet with

\ifx\insertsubsection\empty\else%
 \ifdefempty{\subsecname}{\relax}{%
  ~--~\insertsubsectionhead%
 }%
\fi

and IT WORKS!!!
Unfortunately needs the etoolbox package to be loaded...

EDIT:

\setbox0=\hbox{\subsecname\unskip}\ifdim\wd0=0pt\else%
 ~--~\insertsubsectionhead%
\fi%

also works and does not require etoolbox.
I don't know if this is the "cleaner" solution.

Related