Fixed passing null for number_format is deprecated for downloadable products

[kyrena]

Description

This fix passing null to parameter #1 ($num) of type float is deprecated for number_format with PHP 8.1/8.2.
Perhaps it's not the best way.

See also this discussion comment.

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[kiatng]

Is it better to fix it here:

magento-lts/app/code/core/Mage/Downloadable/Block/Adminhtml/Catalog/Product/Edit/Tab/Downloadable/Links.php

Lines 228 to 230 in bda0b6f

	public function getPriceValue($value)
	{
	return number_format($value, 2, null, '');

[fballiano]

how would you do that? cause if $value is null I don't see what we should return

[kiatng]

Ref https://onlinephp.io/c/5e8d8, when $value = null, it used to return '0.00'. Also, see the docblock:

   /**
     * Return formatted price with two digits after decimal point
     *
     * @param float $value
     * @return string
     */
    public function getPriceValue($value)
    {
       // suggestion:
        if (!$value) {
            return '0.00';
        }
        return number_format($value, 2, null, '');
    }

Note that when $value = '': we have

Fatal error: Uncaught TypeError: number_format(): Argument #1 ($num) must be of type float, string given in /home/user/scripts/code.php:3
Stack trace:
#0 /home/user/scripts/code.php(3): number_format('', 2, NULL, '')