Added some error handling to the Project Samples page

* `console.log` calls when any of the AJAX calls fail
* **Project Not Found** page display when no project is returned, instead of just an empty template
* **No Samples Found** in the samples tab instead of an empty table if no samples..

Stage examples: https://genomics-status-stage.scilifelab.se/project/this_project_doesn't_exist
https://genomics-status-stage.scilifelab.se/project/P920 (samples tab)