error handling when no route is possible
Merge branch 'hydro-devel' of https://github.com/Jailander/strands_navigation into hydro-devel
Merge branch 'hydro-devel' of https://github.com/strands-project/strands_navigation into hydro-devel
Merge pull request #158 from Jailander/hydro-devel

 error handling when no route is possible