private void reportNonNumber(char command, int ch, StringBuffer context)
            throws DatatypeException {
        if (ch != -1) {
            throw newDatatypeException("Expected number for \u201c" + command
                    + "\u201d command but found " + "\u201c" + (char) ch
                    + "\u201d instead " + "(context: \u201c"
                    + context.toString() + "\u201d).");
        } else {
            throw newDatatypeException("Expected number for \u201c" + command
                    + "\u201d command but value ended " + "(context: \u201c"
                    + context.toString() + "\u201d).");
        }
    }
Skips the whitespaces and an optional comma.
src/nu/validator/datatype/SvgPathData.java