I work as a grader for an intro CS class that uses Processing. The software that students use to submit their assignments will append numbers to the filename if a student resubmits their assignment, which gives me something like "assignment-1.pde" when I download it.

When I try to run this file using the command line compiler, I get a crash with the following output:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
        at processing.app.Sketch.getCode(Sketch.java:1644)
        at processing.app.Sketch.getMainProgram(Sketch.java:1669)
        at processing.mode.java.JavaBuild.preprocess(JavaBuild.java:216)
        at processing.mode.java.JavaBuild.preprocess(JavaBuild.java:155)
        at processing.mode.java.JavaBuild.build(JavaBuild.java:122)
        at processing.mode.java.Commander.<init>(Commander.java:274)
        at processing.mode.java.Commander.main(Commander.java:86)

When I try to open the file with the IDE, I get an error there as well:

I get the same error if I change the ending to "-2", so only it seems that ending in "negative" numbers breaks something. Removing the "-1" causes the error to go away given nothing else is wrong with the filename.