message: Fix Improve scanning of label={....}
  When the label contains an '_', its ast representation is split on
  several nodes. We use stringify to rebuild the label.
  The listing ast representation has an optional arg field but no args,
  we handle this case separately.
diff: @@ -169,8 +169,8 @@ export class Reference implements IProvider {
  // \label{some-text}
  label = node.label
  } else if (latexParser.isTextString(node) && node.content === 'label=' && useLabelKeyVal && nextNode !== undefined) {
  - // label={some=text}
  - label = ((nextNode as latexParser.Group).content[0] as latexParser.TextString).content
  + // label={some-text}
  + label = latexParser.stringify(nextNode).slice(1, -1)
  }
  if (label !== '' && (latexParser.isLabelCommand(node) || latexParser.isTextString(node))) {
  refs.push({
  @@ -190,6 +190,12 @@ export class Reference implements IProvider {
  if (latexParser.hasArgsArray(node)) {
  return this.getRefFromNodeArray(node.args, lines)
  }
  + if (latexParser.isLstlisting(node)) {
  + const arg = (node as latexParser.Lstlisting).arg
  + if (arg) {
  + return this.getRefFromNode(arg, lines)
  + }
  + }
  return refs
  }
  