While I try to export my sketch to a .app file (using Processing 2.0.1 under Mac OS X Lion) I get the following exception stack trace:

1. java.lang.NullPointerException
2.     at processing.app.Base.copyDir(Base.java:2530)
3.     at processing.mode.java.JavaBuild.exportApplication(JavaBuild.java:1162)
4.     at processing.mode.java.JavaBuild.exportApplication(JavaBuild.java:1104)
5.     at processing.mode.java.JavaMode.handleExportApplication(JavaMode.java:160)
6.     at processing.mode.java.JavaEditor.exportApplicationPrompt(JavaEditor.java:422)
7.     at processing.mode.java.JavaEditor.handleExportApplication(JavaEditor.java:231)
8.     at processing.mode.java.JavaEditor$1.actionPerformed(JavaEditor.java:55)
9.     at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2028)
10.     at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2351)
11.     at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
12.     at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
13.     at javax.swing.AbstractButton.doClick(AbstractButton.java:389)
14.     at com.apple.laf.ScreenMenuItem.actionPerformed(ScreenMenuItem.java:95)
15.     at java.awt.MenuItem.processActionEvent(MenuItem.java:650)
16.     at java.awt.MenuItem.processEvent(MenuItem.java:609)
17.     at java.awt.MenuComponent.dispatchEventImpl(MenuComponent.java:343)
18.     at java.awt.MenuComponent.dispatchEvent(MenuComponent.java:331)
19.     at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:720)
20.     at java.awt.EventQueue.access$400(EventQueue.java:82)
21.     at java.awt.EventQueue$2.run(EventQueue.java:676)
22.     at java.awt.EventQueue$2.run(EventQueue.java:674)
23.     at java.security.AccessController.doPrivileged(Native Method)
24.     at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:86)
25.     at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:97)
26.     at java.awt.EventQueue$3.run(EventQueue.java:690)
27.     at java.awt.EventQueue$3.run(EventQueue.java:688)
28.     at java.security.AccessController.doPrivileged(Native Method)
29.     at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:86)
30.     at java.awt.EventQueue.dispatchEvent(EventQueue.java:687)
31.     at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296)
32.     at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211)
33.     at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201)
34.     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196)
35.     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188)
36.     at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

Some additional info (if it can be of any help): I'm writing a sketch that uses controlP5, the pdf library and a couple classes written by me (some .pde files and a .java file).

Any ideas?