Charswhile(..,0) with rep will cause infinitely loop

[He-Pin]

  private def `name-first`[_: P]: P[Unit] = P(CharsWhile(isNameFirstAcceptable, 1))

  private def `name-char`[_: P]: P[Unit] = P(CharsWhile(isNameCharAcceptable, 1))

 /**
   * https://www.rfc-editor.org/rfc/rfc9535#section-2.5.1.1
   *
   * {{{
   * member-name-shorthand = name-first *name-char
   * name-first          = ALPHA /
   *                       "_"   /
   *                       %x80-D7FF /
   *                          ; skip surrogate code points
   *                       %xE000-10FFFF
   * name-char           = name-first / DIGIT
   *
   * DIGIT               = %x30-39              ; 0-9
   * ALPHA               = %x41-5A / %x61-7A    ; A-Z / a-z
   * }}}
   * */
  private def `member-name-shorthandIdentifier`[_: P]: P[String] = P(`name-first` ~ `name-char`.rep).!

Works well, but if I change the name-char to 0 then it will never end, eg:

  private def `name-char`[_: P]: P[Unit] = P(CharsWhile(isNameCharAcceptable, 0))

[lihaoyi]

This is expected

[He-Pin]

Thanks