```
jshell> FormatProcessor.FMT."\{return;}"
Exception in thread "main" java.lang.InternalError: Exception during parse - java.lang.AssertionError
        at jdk.jshell/jdk.jshell.TaskFactory$ParseTask.parse(TaskFactory.java:381)
...
Caused by: java.lang.IllegalStateException: java.lang.AssertionError
        at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl.parse(JavacTaskImpl.java:252)
        at jdk.jshell/jdk.jshell.TaskFactory$ParseTask.parse(TaskFactory.java:379)
        ... 24 more
Caused by: java.lang.AssertionError
        at jdk.compiler/com.sun.tools.javac.util.Assert.error(Assert.java:155)
        at jdk.compiler/com.sun.tools.javac.util.Assert.check(Assert.java:46)
        at jdk.compiler/com.sun.tools.javac.parser.JavacParser.reportSyntaxError(JavacParser.java:492)
...
```