Stack trace for failing sketch

gistfile1.txt

grey_circles.rb:10 warning: ambiguous Java methods found, using background(int)
Exception in thread "Animation Thread" org.jruby.exceptions.RaiseException: (IOError) closed stream
	at java.lang.Thread.getStackTrace(java/lang/Thread.java:1552)
	at org.jruby.runtime.backtrace.TraceType$Gather.getBacktraceData(org/jruby/runtime/backtrace/TraceType.java:175)
	at org.jruby.runtime.backtrace.TraceType.getBacktrace(org/jruby/runtime/backtrace/TraceType.java:39)
	at org.jruby.RubyException.prepareBacktrace(org/jruby/RubyException.java:227)
	at org.jruby.exceptions.RaiseException.preRaise(org/jruby/exceptions/RaiseException.java:215)
	at org.jruby.exceptions.RaiseException.preRaise(org/jruby/exceptions/RaiseException.java:194)
	at org.jruby.exceptions.RaiseException.<init>(org/jruby/exceptions/RaiseException.java:110)
	at org.jruby.Ruby.newRaiseException(org/jruby/Ruby.java:3959)
	at org.jruby.Ruby.newIOError(org/jruby/Ruby.java:3848)
	at org.jruby.util.io.OpenFile.checkClosed(org/jruby/util/io/OpenFile.java:662)
	at org.jruby.RubyIO.getOpenFileChecked(org/jruby/RubyIO.java:259)
	at org.jruby.RubyIO.write(org/jruby/RubyIO.java:1422)
	at org.jruby.RubyIO.write(org/jruby/RubyIO.java:1399)
	at org.jruby.RubyClass.finvoke(org/jruby/RubyClass.java:734)
	at org.jruby.runtime.Helpers.invoke(org/jruby/runtime/Helpers.java:595)
	at org.jruby.RubyBasicObject.callMethod(org/jruby/RubyBasicObject.java:368)
	at org.jruby.common.RubyWarnings.warn(org/jruby/common/RubyWarnings.java:87)
	at org.jruby.common.RubyWarnings.warn(org/jruby/common/RubyWarnings.java:121)
	at org.jruby.common.RubyWarnings.warn(org/jruby/common/RubyWarnings.java:52)
	at org.jruby.java.dispatch.CallableSelector.findMatchingCallableForArgs(org/jruby/java/dispatch/CallableSelector.java:133)
	at org.jruby.java.dispatch.CallableSelector.matchingCallableArityOne(org/jruby/java/dispatch/CallableSelector.java:54)
	at org.jruby.java.invokers.RubyToJavaInvoker.findCallableArityOne(org/jruby/java/invokers/RubyToJavaInvoker.java:257)
	at org.jruby.java.invokers.InstanceMethodInvoker.call(org/jruby/java/invokers/InstanceMethodInvoker.java:59)
	at org.jruby.java.invokers.InstanceMethodInvoker.call(org/jruby/java/invokers/InstanceMethodInvoker.java:127)
	at org.jruby.RubyClass.finvoke(org/jruby/RubyClass.java:560)
	at org.jruby.RubyBasicObject.send19(org/jruby/RubyBasicObject.java:1613)
	at org.jruby.RubyKernel.send19(org/jruby/RubyKernel.java:2002)
	at org.jruby.internal.runtime.methods.JavaMethod$JavaMethodOneOrTwoOrNBlock.call(org/jruby/internal/runtime/methods/JavaMethod.java:381)
	at org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(org/jruby/runtime/callsite/CachingCallSite.java:337)
	at org.jruby.runtime.callsite.CachingCallSite.call(org/jruby/runtime/callsite/CachingCallSite.java:199)
	at grey_circles.stroke_setup_CLOSURE_1__stroke_setup_6(grey_circles.rb:21)
	at grey_circles.stroke_setup_CLOSURE_1__stroke_setup_6(grey_circles.rb:21)
	at org.jruby.runtime.CompiledIRBlockBody.commonYieldPath(org/jruby/runtime/CompiledIRBlockBody.java:66)
	at org.jruby.runtime.IRBlockBody.doYield(org/jruby/runtime/IRBlockBody.java:137)
	at org.jruby.runtime.BlockBody.yield(org/jruby/runtime/BlockBody.java:82)
	at org.jruby.runtime.Block.yield(org/jruby/runtime/Block.java:147)
	at org.jruby.RubyArray.each(org/jruby/RubyArray.java:1567)
	at org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(org/jruby/runtime/callsite/CachingCallSite.java:307)
	at org.jruby.runtime.callsite.CachingCallSite.callBlock(org/jruby/runtime/callsite/CachingCallSite.java:145)
	at org.jruby.runtime.callsite.CachingCallSite.call(org/jruby/runtime/callsite/CachingCallSite.java:149)
	at grey_circles.stroke_setup_4(grey_circles.rb:20)
	at grey_circles.stroke_setup_4(grey_circles.rb:20)
	at org.jruby.internal.runtime.methods.CompiledIRMethod.call(org/jruby/internal/runtime/methods/CompiledIRMethod.java:122)
	at org.jruby.internal.runtime.methods.DynamicMethod.call(org/jruby/internal/runtime/methods/DynamicMethod.java:198)
	at org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(org/jruby/runtime/callsite/CachingCallSite.java:297)
	at org.jruby.runtime.callsite.CachingCallSite.call(org/jruby/runtime/callsite/CachingCallSite.java:135)
	at grey_circles.draw_3(grey_circles.rb:14)
	at grey_circles.draw_3(grey_circles.rb:14)
	at org.jruby.internal.runtime.methods.CompiledIRMethod.call(org/jruby/internal/runtime/methods/CompiledIRMethod.java:106)
	at org.jruby.internal.runtime.methods.DynamicMethod.call(org/jruby/internal/runtime/methods/DynamicMethod.java:180)
	at org.jruby.javasupport.proxy.JavaProxyConstructor$2.invoke(org/jruby/javasupport/proxy/JavaProxyConstructor.java:224)
	at processing.core.PApplet.handleDraw(processing/core/PApplet.java:2386)
	at processing.core.PGraphicsJava2D.requestDraw(processing/core/PGraphicsJava2D.java:240)
	at processing.core.PApplet.run(processing/core/PApplet.java:2256)
	at java.lang.Thread.run(java/lang/Thread.java:745)

if the main therad exits sometimes jruby can close file descriptors...