Running Java code with no class produces a cryptic stack trace

[ctrueden]

Start a new Java script in the Script Editor. Add (only!) the following code:

System.out.println("Hello");

And save it as Hello.java. Then try to run it. The following exception is printed:

Started Hello.java at Fri Aug 07 13:52:47 CDT 2020
java.lang.NullPointerException
	at org.scijava.minimaven.MavenProject$XMLHandler.endElement(MavenProject.java:1531)
	at org.apache.xerces.parsers.AbstractSAXParser.endElement(Unknown Source)
	at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanEndElement(Unknown Source)
	at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(Unknown Source)
	at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
	at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
	at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
	at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
	at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
	at org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown Source)
	at org.scijava.minimaven.MavenProject.parse(MavenProject.java:1480)
	at org.scijava.minimaven.BuildEnvironment.parse(BuildEnvironment.java:217)
	at org.scijava.plugins.scripting.java.JavaEngine.fakePOM(JavaEngine.java:748)
	at org.scijava.plugins.scripting.java.JavaEngine.writeTemporaryProject(JavaEngine.java:630)
	at org.scijava.plugins.scripting.java.JavaEngine.getMavenProject(JavaEngine.java:530)
	at org.scijava.plugins.scripting.java.JavaEngine.access$700(JavaEngine.java:96)
	at org.scijava.plugins.scripting.java.JavaEngine$Builder.initialize(JavaEngine.java:405)
	at org.scijava.plugins.scripting.java.JavaEngine$Builder.access$100(JavaEngine.java:364)
	at org.scijava.plugins.scripting.java.JavaEngine.compile(JavaEngine.java:197)
	at org.scijava.plugins.scripting.java.JavaEngine.eval(JavaEngine.java:136)
	at org.scijava.script.ScriptModule.run(ScriptModule.java:157)
	at org.scijava.module.ModuleRunner.run(ModuleRunner.java:165)
	at org.scijava.module.ModuleRunner.call(ModuleRunner.java:124)
	at org.scijava.module.ModuleRunner.call(ModuleRunner.java:63)
	at org.scijava.thread.DefaultThreadService.lambda$wrap$2(DefaultThreadService.java:225)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)
java.lang.IllegalArgumentException: Unknown code type: null
	at org.scijava.run.RunService.run(RunService.java:60)
	at org.scijava.plugins.scripting.java.JavaEngine.eval(JavaEngine.java:137)
	at org.scijava.script.ScriptModule.run(ScriptModule.java:157)
	at org.scijava.module.ModuleRunner.run(ModuleRunner.java:165)
	at org.scijava.module.ModuleRunner.call(ModuleRunner.java:124)
	at org.scijava.module.ModuleRunner.call(ModuleRunner.java:63)
	at org.scijava.thread.DefaultThreadService.lambda$wrap$2(DefaultThreadService.java:225)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)

Certainly the java.lang.IllegalArgumentException: Unknown code type: null at org.scijava.run.RunService.run(RunService.java:60) part is a bug here in SJC. The first part, an NPE in minimaven, may need to be addressed there instead.

[imagejan]

I wonder if this line is correct:

scijava-common/src/main/java/org/scijava/script/run/ScriptCodeRunner.java

Line 101 in a5993b3

else if (code instanceof String) scriptFile = new File((String) code);

If we get a String, do we want to interpret it as a filename here? What if the String contains the actual script code?