fixed NPE

org.fortiss.tooling.kernel/trunk/src/org/fortiss/tooling/kernel/internal/storage/eclipse/ModelContext.java

@@ -152,6 +152,10 @@ class ModelContext implements ITopLevelElement {
 	/** {@inheritDoc} */
 	@Override
 	public void prepareIDs(EObject other) {
+		if (other == null) {
+			return;
+		}
+
 		boolean needSmart = false;
 		if (other instanceof IIdLabeled) {
 			if (((IIdLabeled) other).getId() <= 0) {