use haddadin automaton as example PN, print PNML framework error messages

src/main/java/de/tudresden/inf/st/pnml/Main.java

@@ -25,8 +25,9 @@ public class Main {
 
   public static void main(String[] args) {
 
-    String fileName = "src/main/resources/minimal.pnml";
+//    String fileName = "src/main/resources/minimal.pnml";
 //    String fileName = "src/main/resources/philo.pnml";
+    String fileName = "src/main/resources/haddadin_automaton_flat.pnml";
 
     List<PetriNet> petriNets = parsePnml(fileName);
 
@@ -67,6 +68,7 @@ public class Main {
       logger.info(document.toPNML());
     } catch (ImportException | InvalidIDException e) {
       logger.error("Unable to import PNML document from file '{}'", fileName);
+      logger.error("Exception was thrown!", e);
       System.exit(-1);
     }