Crash in rep by entering \, enter, enter.

[PieterOlivier]

Describe the bug

If you start a new repl and enter a backslash () followed by two "enter" keypresses the repl crashes.

Repl output

Version: Rascal version not specified in META-INF/MANIFEST.MF???
rascal>\
│2 >>>>
Unexpected (uncaught) exception, closing the REPL:
java.lang.IndexOutOfBoundsException: start 1, end 2, length 1java.lang.IndexOutOfBoundsException: start 1, end 2, length 1
        at java.base/java.lang.AbstractStringBuilder.checkRange(AbstractStringBuilder.java:1716)
        at java.base/java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:631)
        at java.base/java.lang.StringBuilder.append(StringBuilder.java:217)
        at org.jline.jansi.Ansi.a(Ansi.java:781)
        at org.rascalmpl.repl.rascal.ParseErrorPrinter.writeUnderLine(ParseErrorPrinter.java:121)
        at org.rascalmpl.repl.rascal.ParseErrorPrinter.highlightErrorInInput(ParseErrorPrinter.java:205)
        at org.rascalmpl.repl.rascal.ParseErrorPrinter.buildPromptError(ParseErrorPrinter.java:129)
        at org.rascalmpl.repl.rascal.ParseErrorPrinter.parseErrorMaybePrompt(ParseErrorPrinter.java:68)
        at org.rascalmpl.repl.rascal.RascalReplServices.handleInput(RascalReplServices.java:112)
        at org.rascalmpl.repl.BaseREPL.handleInput(BaseREPL.java:213)
        at org.rascalmpl.repl.BaseREPL.run(BaseREPL.java:130)
        at org.rascalmpl.shell.REPLRunner.run(REPLRunner.java:34)
        at org.rascalmpl.shell.RascalShell.main(RascalShell.java:53)

Version info
Latest version of Rascal on the main branch (commit id: #2bb56f8d4b8eedba74fe03aba588d5c8783ca192)