Fixed transaction not getting closed

Fixes #16

server/src/main/java/envoy/server/data/PersistenceManager.java

@@ -3,9 +3,7 @@ package envoy.server.data;
 import java.time.Instant;
 import java.util.List;
 
-import javax.persistence.EntityManager;
-import javax.persistence.EntityTransaction;
-import javax.persistence.Persistence;
+import javax.persistence.*;
 
 import envoy.data.User.UserStatus;
 import envoy.server.net.ConnectionManager;
@@ -235,8 +233,8 @@ public final class PersistenceManager {
 	public void addContactBidirectional(long contactID1, long contactID2) {
 
 		// Get users by ID
-		Contact	c1	= getContactByID(contactID1);
-		Contact	c2	= getContactByID(contactID2);
+		final var	c1	= getContactByID(contactID1);
+		final var	c2	= getContactByID(contactID2);
 
 		// Add users to each others contact lists
 		c1.getContacts().add(c2);
@@ -259,20 +257,47 @@ public final class PersistenceManager {
 	}
 
 	private void persist(Object obj) {
-		transaction.begin();
-		entityManager.persist(obj);
-		transaction.commit();
+		try {
+			transaction.begin();
+			entityManager.persist(obj);
+			transaction.commit();
+
+			// Last transaction threw an error resulting in the transaction not being closed
+		} catch (final IllegalStateException e) {
+			if (transaction.isActive()) {
+				transaction.rollback();
+				persist(obj);
+			}
+		}
 	}
 
 	private void merge(Object obj) {
-		transaction.begin();
-		entityManager.merge(obj);
-		transaction.commit();
+		try {
+			transaction.begin();
+			entityManager.merge(obj);
+			transaction.commit();
+
+			// Last transaction threw an error resulting in the transaction not being closed
+		} catch (final IllegalStateException e) {
+			if (transaction.isActive()) {
+				transaction.rollback();
+				merge(obj);
+			}
+		}
 	}
 
 	private void remove(Object obj) {
-		transaction.begin();
-		entityManager.remove(obj);
-		transaction.commit();
+		try {
+			transaction.begin();
+			entityManager.remove(obj);
+			transaction.commit();
+
+			// Last transaction threw an error resulting in the transaction not being closed
+		} catch (final IllegalStateException e) {
+			if (transaction.isActive()) {
+				transaction.rollback();
+				remove(obj);
+			}
+		}
 	}
 }