Regular expressions over labeled symbols leak compilation errors

[rodinaarssen]

Describe the bug

For most variants (Sym?, Sym*, Sym+, {Sym _}*, {Sym _}+), injecting a labeled symbol leaks a Java compilation error.

To Reproduce

Steps to reproduce the behavior:

rascal>lexical A = "a";
ok
rascal>syntax B = A error*;
ok
rascal>parse(#B, "")
org.rascalmpl.exceptions.JavaCompilation: Java compilation failed due to method A() is already defined in class org.rascalmpl.java.parser.object.ParseTree_711466693 at 231, 44 with classpath [c:\Users\Rodin\.vscode\extensions\usethesource.rascalmpl-0.1.5\assets\jars\rascal-lsp.jar;c:\Users\Rodin\.vscode\extensions\usethesource.rascalmpl-0.1.5\assets\jars\rascal.jar]
(internal error)
        at $shell$(|main://$shell$|)

org.rascalmpl.exceptions.JavaCompilation: Java compilation failed due to method A() is already defined in class org.rascalmpl.java.parser.object.ParseTree_711466693 at 231, 44 with classpath [c:\Users\Rodin\.vscode\extensions\usethesource.rascalmpl-0.1.5\assets\jars\rascal-lsp.jar;c:\Users\Rodin\.vscode\extensions\usethesource.rascalmpl-0.1.5\assets\jars\rascal.jar]
        at org.rascalmpl.interpreter.utils.JavaBridge.compileJava(JavaBridge.java:126)
        at org.rascalmpl.interpreter.utils.JavaBridge.compileJava(JavaBridge.java:109)
        at org.rascalmpl.parser.ParserGenerator.getNewParser(ParserGenerator.java:261)
        at org.rascalmpl.parser.ParserGenerator.getNewParser(ParserGenerator.java:223)
        at org.rascalmpl.semantics.dynamic.Import.getParser(Import.java:582)
        at org.rascalmpl.interpreter.Evaluator.getObjectParser(Evaluator.java:773)
...

Desktop (please complete the following information):

• Context: VSCode 0.1.5
• Rascal 0.19.6