clean up code to avoid "Use of uninitialized value in concatenation.."

git-svn-id: svn://svn.code.sf.net/p/fhem/code@5207 2b470e98-0d58-463d-a4d8-8e2adae1ed80
add changes to changed file

git-svn-id: svn://svn.code.sf.net/p/fhem/code@5208 2b470e98-0d58-463d-a4d8-8e2adae1ed80