Sample extension's About page errors

The About page for the sample extension fails to render.

To Reproduce

Steps to reproduce the behavior:

1. Go to http://127.0.0.1:3333/extension/sample/

Current Results

(From new Butterfly error page for improve readability)

HTTP ERROR 500 Butterfly Error Butterfly caught the following error while processing the request:

URI: | /extension/sample/ -- | -- 500 Butterfly Error Butterfly caught the following error while processing the request: refine org.mozilla.javascript.EcmaError: TypeError: Cannot call property stringArrayLength in object [JavaPackage com.google.refine.sampleExtension.SampleUtil]. It is not a function, it is "object". (file:/Users/tfmorris/git/OpenRefine2/main/webapp/../../extensions/sample/module/MOD-INF/controller.js#75)

Caused by:

org.mozilla.javascript.EcmaError: TypeError: Cannot call property stringArrayLength in object [JavaPackage com.google.refine.sampleExtension.SampleUtil]. It is not a function, it is "object". (file:/Users/tfmorris/git/OpenRefine2/main/webapp/../../extensions/sample/module/MOD-INF/controller.js#75)
	at org.mozilla.javascript.ScriptRuntime.constructError(ScriptRuntime.java:4563)
	at org.mozilla.javascript.ScriptRuntime.constructError(ScriptRuntime.java:4544)
	at org.mozilla.javascript.ScriptRuntime.typeError(ScriptRuntime.java:4576)
	at org.mozilla.javascript.ScriptRuntime.typeErrorById(ScriptRuntime.java:4581)
	at org.mozilla.javascript.ScriptRuntime.notFunctionError(ScriptRuntime.java:4662)
	at org.mozilla.javascript.ScriptRuntime.getPropFunctionAndThisHelper(ScriptRuntime.java:2585)
	at org.mozilla.javascript.ScriptRuntime.getPropFunctionAndThis(ScriptRuntime.java:2568)
	at org.mozilla.javascript.gen.file__Users_tfmorris_git_OpenRefine2_main_webapp_______extensions_sample_module_MOD_INF_controller_js_18._c_process_2(file:/Users/tfmorris/git/OpenRefine2/main/webapp/../../extensions/sample/module/MOD-INF/controller.js:75)
	at org.mozilla.javascript.gen.file__Users_tfmorris_git_OpenRefine2_main_webapp_______extensions_sample_module_MOD_INF_controller_js_18.call(file:/Users/tfmorris/git/OpenRefine2/main/webapp/../../extensions/sample/module/MOD-INF/controller.js)
	at org.mozilla.javascript.ContextFactory.doTopCall(ContextFactory.java:380)
	at org.mozilla.javascript.ScriptRuntime.doTopCall(ScriptRuntime.java:3868)
	at org.mozilla.javascript.gen.file__Users_tfmorris_git_OpenRefine2_main_webapp_______extensions_sample_module_MOD_INF_controller_js_18.call(file:/Users/tfmorris/git/OpenRefine2/main/webapp/../../extensions/sample/module/MOD-INF/controller.js)
	at edu.mit.simile.butterfly.ButterflyModuleImpl$Controller.process(ButterflyModuleImpl.java:399)
	at edu.mit.simile.butterfly.ButterflyModuleImpl$Controller.run(ButterflyModuleImpl.java:377)
	at org.mozilla.javascript.Context.call(Context.java:535)
	at org.mozilla.javascript.ContextFactory.call(ContextFactory.java:472)
	at edu.mit.simile.butterfly.ButterflyModuleImpl.processScript(ButterflyModuleImpl.java:654)
	at edu.mit.simile.butterfly.ButterflyModuleImpl.process(ButterflyModuleImpl.java:427)
	at edu.mit.simile.butterfly.Butterfly.service(Butterfly.java:524)
	at com.google.refine.RefineServlet.service(RefineServlet.java:217)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:750)

Expected Behavior

Velocity template renders correctly.

Versions

• OpenRefine: 3.7 and current HEAD of master (not sure how far back it goes)

Additional context

At first glance it looks like perhaps the SampleUtil class isn't getting compiled or packaged in the right place.

Start at extensions/sample/module/MOD-INF/controller.js line 75 and inspect how it calls com.google.refine.sampleExtension.SampleUtil. Then check where SampleUtil is compiled or packaged, since the error shows it is exposed as a JavaPackage rather than the expected class. Done means visiting /extension/sample/ renders the About page's Velocity template without an HTTP 500 error.