Quantity numbers are added like strings in offline mode

[ArturDivante]

Current behavior

Adding another products result in summing their quantity digits instead of values (see video).

Expected behavior

Product quantities should be summed correctly in offline mode.

Steps to reproduce the issue

1. Open https://test.storefrontcloud.io/ and then any category page
2. Turn to offline mode
3. Open product page and add some quantity to cart
4. Open another product page and again add some quantity to cart

Repository

test.storefrontcloud.io

Can you handle fixing this bug by yourself?

no

Environment details

• Browser: many
• OS: win10

Additional information

Sometimes problem is tricky to reproduce. Trying with few diffrent products (as described in steps) makes it easier to recreate.

Important update!

I just noticed, that problem in some way occurs also in online mode.

1. Adding 2nd product (with any quantity) to the cart briefly results in displaying incorrect number on the cart icon - but it gets recalculated correctly within a second
2. If we quickly click "add to cart" button few times, incorrectly high quantities might really be added to cart. Example:
   We set quantity number to 5 and then quickly click "add to cart" few times, we may add 55 items instead of 5,10,15 etc. If only stock supply allow for that, we will add incorrectly high number of products to the cart

[ArturDivante]

Important update! - I just noticed, that problem in some way occurs also in online mode.

1. Adding 2nd product (with any quantity) to the cart briefly results in displaying incorrect number on the cart icon - but it gets recalculated correctly within a second
2. If we quickly click "add to cart" button few times, incorrectly high quantities might really be added to cart. Example:
   We set quantity number to 5 and then quickly click "add to cart" few times, we may add 55 items instead of 5,10,15 etc. If only stock supply allow for that, we will add incorrectly high number of products to the cart