ST6RI-178 Added error message for empty branch loading

Author: TheKorpos

org.omg.sysml.interactive/src/org/omg/sysml/interactive/SysMLInteractive.java

@@ -538,6 +538,11 @@ private String load(RemoteBranch branch) {
 		System.out.println();
 		System.out.println("Selected branch " + branch.getName() + " (" + branch.getRemoteId().toString() + ")");
 
+		Revision headRevision = branch.getHeadRevision();
+		if (!headRevision.isRemote()) {
+			return "ERROR:Branch has no head commit\n";
+		}
+		
 		if (!tracker.isLibraryTracked()) {
 			System.out.println("Caching library UUIDs...");
 			tracker.trackLibraryUUIDs(getLibraryResources());
@@ -549,9 +554,6 @@ private String load(RemoteBranch branch) {
 		tracker.trackLocalUUIDs(inputResources);
 
 		System.out.println("Downloading model...");
-		
-		RemoteProject remoteProject = branch.getRemoteProject();
-		Revision headRevision = branch.getHeadRevision();
 		APIModel model = headRevision.fetchRemote();
 
 		EMFModelRefresher modelRefresher = new EMFModelRefresher(model, tracker);
@@ -565,6 +567,7 @@ private String load(RemoteBranch branch) {
 			addResourceToIndex(resource);
 		});
 
+		RemoteProject remoteProject = branch.getRemoteProject();
 		return "Loaded Project " + remoteProject.getProjectName() + " (" + remoteProject.getRemoteId().toString() + ")\n";
 	}