message: Fix no completion for double backslash
  This commit fixes and closes
diff: @@ -49,7 +49,7 @@ export class Completer implements vscode.CompletionItemProvider {
  return new Promise((resolve, _reject) => {
  const invokeChar = document.lineAt(position.line).text[position.character - 1]
  const currentLine = document.lineAt(position.line).text
  - if (position.character > 1 && currentLine[position.character - 2] === '\\') {
  + if (position.character > 1 && currentLine[position.character - 1] === '\\' && currentLine[position.character - 2] === '\\') {
  resolve()
  return
  }
  