fix transaction handling

qserv/src/main/java/de/hsadmin/core/model/Transaction.java

@@ -108,8 +108,12 @@ public class Transaction {
 	}
 
 	public void commitTransaction() {
+		try {
+			entityManager.getTransaction().commit();
+		} catch (Exception e) {
+			throw new TechnicalException(e);
+		}		
 		sendAll();
-		entityManager.getTransaction().commit();		
 		transactionActive = false;
 	}
 
@@ -119,7 +123,7 @@ public class Transaction {
 		try {
 			entityManager.getTransaction().rollback();
 		} catch (IllegalStateException e) {
-			// can't rollback 
+			throw new TechnicalException(e);
 		}
 	}