Steps to reproduce:

Create empty project

Try to export using

Spine 

---

input test.spine 

---

export export.json

Works fine
Add path

Try to export using

Spine 

---

input test.spine 

---

export export.json

Observe crash:

java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at java.lang.invoke.MethodHandleImpl$BindCaller$T/15650644.invoke_V(MethodHandleImpl.java:933)
        at tzax.w.run(SourceFile:1540)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:302)
        at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:745)
        at java.awt.EventQueue.access$300(EventQueue.java:103)
        at java.awt.EventQueue$3.run(EventQueue.java:706)
        at java.awt.EventQueue$3.run(EventQueue.java:704)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:715)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
Caused by: java.lang.ArrayIndexOutOfBoundsException: 0
        at mN.a(SourceFile:89)
        at mH.a(SourceFile:53)
        at AK.g(SourceFile:79)
        at sW.a(SourceFile:436)
        at sW.a(SourceFile:286)
        at sW.a(SourceFile:94)
        at tb.a(SourceFile:70)
        at lW.a(SourceFile:113)
        at lW.a(SourceFile:70)
        at com.esotericsoftware.spine.editor.Editor.a(SourceFile:1323)
        at com.esotericsoftware.spine.editor.Editor.main(SourceFile:1296)
        ... 20 more

Exporting using UI works.

Spine Launcher 3.5.21
Spine 3.3.07