omit npe

src/main/java/de/jottyfan/bico/modules/CommonController.java

@@ -29,7 +29,7 @@ public abstract class CommonController {
 
 	@ModelAttribute("isCampAdmin")
 	public Boolean isCampAdmin(Principal principal) {
-		return admins.contains(principal.getName());
+		return principal == null ? false : admins.contains(principal.getName());
 	}
 
 	@ModelAttribute("hasBUrole")