Addon to add external links to openHAB dashboard

Hi i just tried to add my own links by editing the dashboard.cfg, but then my dashboard stopped working. Now i restored my dashboard.cfg but it still doesn’t work. How can i fix it?

Here is what the browser shows:

HTTP ERROR 500

Problem accessing /start/index. Reason:

    Server Error

Caused by:

java.lang.NullPointerException
	at java.util.regex.Matcher.quoteReplacement(Matcher.java:701)
	at org.openhab.ui.dashboard.internal.DashboardServlet.lambda$1(DashboardServlet.java:208)
	at org.openhab.ui.dashboard.internal.DashboardServlet.replaceKeysWithFunction(DashboardServlet.java:217)
	at org.openhab.ui.dashboard.internal.DashboardServlet.replaceKeysFromMap(DashboardServlet.java:207)
	at org.openhab.ui.dashboard.internal.DashboardServlet.serveDashboard(DashboardServlet.java:96)
	at org.openhab.ui.dashboard.internal.DashboardServlet.doGet(DashboardServlet.java:80)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
	at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:848)
	at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:584)
	at org.ops4j.pax.web.service.jetty.internal.HttpServiceServletHandler.doHandle(HttpServiceServletHandler.java:71)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
	at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:548)
	at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:226)
	at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1180)
	at org.ops4j.pax.web.service.jetty.internal.HttpServiceContext.doHandle(HttpServiceContext.java:284)
	at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:512)
	at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185)
	at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1112)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
	at org.ops4j.pax.web.service.jetty.internal.JettyServerHandlerCollection.handle(JettyServerHandlerCollection.java:80)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:134)
	at org.eclipse.jetty.server.Server.handle(Server.java:534)
	at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:333)
	at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:251)
	at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:283)
	at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:108)
	at org.eclipse.jetty.io.SelectChannelEndPoint$2.run(SelectChannelEndPoint.java:93)
	at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.executeProduceConsume(ExecuteProduceConsume.java:303)
	at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.produceConsume(ExecuteProduceConsume.java:148)
	at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.run(ExecuteProduceConsume.java:136)
	at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:671)
	at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:589)
	at java.lang.Thread.run(Thread.java:748)