Why I get Exception in Application start method while trying to run JavaFX project?

Question

I'm trying to modify some behavior of a Unicenta POS and Chromis POS kitchen screen program. I downloaded both, the source code for Unicenta and Chromis that is a netbeans project. Both projects can be build successfully but when I try to run them the "Exception in Application start method" appears. I'm with JDK8 and other applications run with JavaFX with no problem. I tested with other machines and happens the same.

ant -f C:\\Users\\Workstation\\Documents\\NetBeansProjects\\uniCenta_Remote_Display\\nbbuild.xml 

jfxsa-run
jfxsa-run:
init:
Deleting: C:\Users\Workstation\Documents\NetBeansProjects\uniCenta_Remote_Display\build\built-jar.properties
deps-jar:
Updating property file: C:\Users\Workstation\Documents\NetBeansProjects\uniCenta_Remote_Display\build\built-jar.properties
compile:
Deleting directory C:\Users\Workstation\Documents\NetBeansProjects\uniCenta_Remote_Display\dist\lib
Copying 17 files to C:\Users\Workstation\Documents\NetBeansProjects\uniCenta_Remote_Display\dist\lib
Detected JavaFX Ant API version 1.3
jfx-deployment:
deploy:
jar:
Copying 20 files to C:\Users\Workstation\Documents\NetBeansProjects\uniCenta_Remote_Display\dist\run189111573
jfx-project-run:
Executing C:\Users\Workstation\Documents\NetBeansProjects\uniCenta_Remote_Display\dist\run189111573\unicenta_remotedisplay.jar using platform C:\Program Files\Java\jdk1.8.0_291\jre/bin/java
May 21, 2021 6:40:17 PM com.unicenta.forms.AppConfig <init>
INFO: Reading configuration file: C:\Users\Workstation\remote_display.properties
May 21, 2021 6:40:18 PM org.hibernate.annotations.common.reflection.java.JavaReflectionManager <clinit>
INFO: HCANN000001: Hibernate Commons Annotations {4.0.5.Final}
May 21, 2021 6:40:18 PM org.hibernate.Version logVersion
INFO: HHH000412: Hibernate Core {4.3.10.Final}
May 21, 2021 6:40:18 PM org.hibernate.cfg.Environment <clinit>
INFO: HHH000206: hibernate.properties not found
May 21, 2021 6:40:18 PM org.hibernate.cfg.Environment buildBytecodeProvider
INFO: HHH000021: Bytecode provider name : javassist
May 21, 2021 6:40:18 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure
WARN: HHH000402: Using Hibernate built-in connection pool (not for production use!)
May 21, 2021 6:40:18 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH000401: using driver [com.mysql.jdbc.Driver] at URL [jdbc:mysql://localhost:3306/unicentaopos]
May 21, 2021 6:40:18 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH000046: Connection properties: {user=, password=****}
May 21, 2021 6:40:18 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH000006: Autocommit mode: false
May 21, 2021 6:40:18 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure
INFO: HHH000115: Hibernate connection pool size: 5 (min=1)
Exception in Application start method
java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
    at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:873)
Caused by: java.lang.RuntimeException: Exception in Application start method
    at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$1(LauncherImpl.java:182)
    at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException
    at com.unicenta.remotedisplay.RemoteDisplay.start(RemoteDisplay.java:73)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$8(LauncherImpl.java:863)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$7(PlatformImpl.java:326)
    at com.sun.javafx.application.PlatformImpl.lambda$null$5(PlatformImpl.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$6(PlatformImpl.java:294)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$4(WinApplication.java:185)
    ... 1 more
Exception running application com.unicenta.remotedisplay.RemoteDisplay
Java Result: 1
Deleting directory C:\Users\Workstation\Documents\NetBeansProjects\uniCenta_Remote_Display\dist\run189111573
jfxsa-run-no-another-jvm:
BUILD SUCCESSFUL (total time: 10 seconds)

This is the source code for unicenta kitchen screen and chromis kitchen screen respectively:

https://mega.nz/file/6qh1AAKI#Uu2b0AseM6pL_UGAhWqIMvG6SusrSpBQiSd5hvsm7jI

https://mega.nz/file/23xHAaZT#yaLtoblY1KWb-gg5-4UuckP3oxVgSpMtSfr842RrUcg

Thanks in advance.