private boolean separatorOrCompleteWith(final char endCharacter) throws StringTagParseException {
    if (this.buffer.takeIf(endCharacter)) {
      return true;
    }
    this.buffer.expect(Tokens.VALUE_SEPARATOR);
    return this.buffer.takeIf(endCharacter);
  }
A tag that is definitely some sort of scalar.

<p>Does not detect quoted strings, so those should have been parsed already.</p>

@return a parsed tag
nbt/src/main/java/net/kyori/adventure/nbt/TagStringReader.java