_getNumber(decimalCharacter) {
        this._skipSpaces();

        const startIndex = this.index;
        while (this.index <= this.textLength && AutoNumericHelper.isDigit(this.text[this.index])) { // Integer part
            this.index++;
        }

        if (this.text[this.index] === decimalCharacter) {
            this.index++;
        }

        while (this.index <= this.textLength && AutoNumericHelper.isDigit(this.text[this.index])) { // Decimal part, if any
            this.index++;
        }

        if (this.index === startIndex) {
            throw new Error(`No number has been found while it was expected`);
        }

        // Convert the localized float number to a Javascript number
        return this.text.substring(startIndex, this.index).replace(decimalCharacter, '.');
    }
Return the integer or float number starting from the `this.index` string index

@param {string} decimalCharacter The decimal character to use in the float numbers

@returns {string}
@private