IIOBE in parsing

[timboudreau]

While editing a Rust source file - if it cannot be avoided, better to catch it and throw a ParseException that the highlighter can deal with:

java.lang.IndexOutOfBoundsException: Index 0 out-of-bounds for length 0
	at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64)
	at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70)
	at java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:248)
	at java.base/java.util.Objects.checkIndex(Objects.java:372)
	at java.base/java.util.ArrayList.get(ArrayList.java:440)
	at com.github.drrb.rust.netbeans.parsing.javacc.JJTRustParserState.rootNode(JJTRustParserState.java:38)
	at com.github.drrb.rust.netbeans.parsing.javacc.RustParser$Result.rootNode(RustParser.java:14)
	at com.github.drrb.rust.netbeans.parsing.NetbeansRustParser$NetbeansRustParserResult.rootNode(NetbeansRustParser.java:89)
	at com.github.drrb.rust.netbeans.highlighting.RustSemanticAnalyzer.run(RustSemanticAnalyzer.java:53)
	at com.github.drrb.rust.netbeans.highlighting.RustSemanticAnalyzer.run(RustSemanticAnalyzer.java:42)
[catch] at org.netbeans.modules.csl.editor.semantic.SemanticHighlighter.process(SemanticHighlighter.java:278)
	at org.netbeans.modules.csl.editor.semantic.SemanticHighlighter.access$000(SemanticHighlighter.java:57)
	at org.netbeans.modules.csl.editor.semantic.SemanticHighlighter$1.run(SemanticHighlighter.java:108)
	at org.netbeans.modules.parsing.impl.TaskProcessor.callUserTask(TaskProcessor.java:586)
	at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:130)
	at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:114)
	at org.netbeans.modules.parsing.impl.TaskProcessor$2.call(TaskProcessor.java:181)
	at org.netbeans.modules.parsing.impl.TaskProcessor$2.call(TaskProcessor.java:178)
	at org.netbeans.modules.masterfs.filebasedfs.utils.FileChangedManager.priorityIO(FileChangedManager.java:153)
	at org.netbeans.modules.masterfs.providers.ProvidedExtensions.priorityIO(ProvidedExtensions.java:335)
	at org.netbeans.modules.parsing.nb.DataObjectEnvFactory.runPriorityIO(DataObjectEnvFactory.java:118)
	at org.netbeans.modules.parsing.impl.Utilities.runPriorityIO(Utilities.java:67)
	at org.netbeans.modules.parsing.impl.TaskProcessor.runUserTask(TaskProcessor.java:178)
	at org.netbeans.modules.parsing.api.ParserManager.parse(ParserManager.java:81)
	at org.netbeans.modules.csl.editor.semantic.SemanticHighlighter.run(SemanticHighlighter.java:98)
	at org.netbeans.modules.csl.editor.semantic.SemanticHighlighter.run(SemanticHighlighter.java:57)
	at org.netbeans.modules.parsing.impl.TaskProcessor.callParserResultTask(TaskProcessor.java:561)
	at org.netbeans.modules.parsing.impl.TaskProcessor$RequestPerformer.run(TaskProcessor.java:786)
	at org.openide.util.lookup.Lookups.executeWith(Lookups.java:279)
	at org.netbeans.modules.parsing.impl.TaskProcessor$RequestPerformer.execute(TaskProcessor.java:702)
	at org.netbeans.modules.parsing.impl.TaskProcessor$CompilationJob.run(TaskProcessor.java:663)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:514)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1418)
	at org.netbeans.modules.openide.util.GlobalLookup.execute(GlobalLookup.java:45)
	at org.openide.util.lookup.Lookups.executeWith(Lookups.java:278)
	at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2033)