Fix the error of product price must be set

[Azouz-Jribi]

Questions	Answers
Branch?	1.6.1.x
Description?	When you create an order with the price of the product = 0 and you try to change the quantity, an error message appears "Error: the price of the product must be set".
Type?	bug fix
Category?	BO
BC breaks?	no
Deprecations?	no
Fixed ticket?	http://forge.prestashop.com/browse/PSCSX-8761 and Fixes #9830
How to test?	BO > create a new product (P) with price = 0, FO > order product P, BO > the order details page, try to change the quantity of the product and check if the error message "Error: The price of the product must be set" is not displayed

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This change is 

[LittleBigDev]

Reviewed 1 of 1 files at r1.
Review status: all files reviewed at latest revision, 1 unresolved discussion.

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js/admin/orders.js, line 671 at r1 (raw file):

		e.preventDefault();
		var $productLineRow = $(this).closest('tr.product-line-row');

I suggest, as you started, creating all needed variables. Not only $productLineRow but also $editProductQuantity, $editProductPrice, $totalProduct, etc...
This way, you will separate selectors assignations and business logic. Logic will be easier to read and maintain.

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Comments from Reviewable

[LittleBigDev]

See comment above

[Azouz-Jribi]

Hi @LittleBigDev
Can you check it ?

Thanks :)

[LittleBigDev]

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Reviewed 1 of 1 files at r2.
Review status: all files reviewed at latest revision, all discussions resolved, some commit checks broke.

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Comments from Reviewable

[matks]

@marionf if this bug is still happening in 1.7, we should be able to fix it thanks to this PR

[khouloudbelguith]

@matks, @marionf => issue reported here: #9830

Thanks!

[Progi1984]

New PR on develop branch : #16392

[matks]

#16392 was merged 🎉 thanks @Azouz-Jribi