public String getParserErrorMessage(Parser parser, RecognitionException e) {
		String msg;
		if ( e instanceof NoViableAltException) {
			String name = parser.getTokenErrorDisplay(e.token);
			msg = name+" came as a complete surprise to me";
		}
		else if ( e instanceof v4ParserException) {
			msg = ((v4ParserException)e).msg;
		}
		else {
			msg = parser.getErrorMessage(e, parser.getTokenNames());
		}
		return msg;
	}
Override error handling for use with ANTLR tool itself; leaves
 nothing in grammar associated with Tool so others can use in IDEs, ...
tool/src/org/antlr/v4/parse/ToolANTLRParser.java