src/errors.js
function duplicateRuleDeclaration(ruleName, grammarName, declGrammarName, optSource) {
  var message = "Duplicate declaration for rule '" + ruleName +
      "' in grammar '" + grammarName + "'";
  if (grammarName !== declGrammarName) {
    message += " (originally declared in '" + declGrammarName + "')";
  }
  return createError(message, optSource);
}
function duplicateRuleDeclaration(ruleName, grammarName, declGrammarName, optSource) {
  var message = "Duplicate declaration for rule '" + ruleName +
      "' in grammar '" + grammarName + "'";
  if (grammarName !== declGrammarName) {
    message += " (originally declared in '" + declGrammarName + "')";
  }
  return createError(message, optSource);
}
function duplicateRuleDeclaration ( ruleName , grammarName , declGrammarName , optSource ) { var message = "Duplicate declaration for rule '" + ruleName + "' in grammar '" + grammarName + "'" ; if ( grammarName !== declGrammarName ) { message += " (originally declared in '" + declGrammarName + "')" ; } return createError ( message , optSource ) ; }
Duplicate rule declaration
Duplicate rule declaration