BO - Export current theme throw an exception when we create a custom language

[khouloudbelguith]

Prerequisites

• I understand and accept the project's code of conduct
• I have already searched in existing issues and found no previous report of this bug.

Describe the bug and add screenshots

A custom language is manually created, In the BO > Design > Theme & Logo page, when we export the current theme, an exception displayed

Expected behavior

Ping @PrestaShop/product-team what do you think?
We should have a red alert that the language is not available, for example

Or the theme should be well downloaded?

Steps to reproduce

1. Go to BO > International > Localization > Languages page
2. Add a new language, in my case
   
3. Save
4. Go to BO > Design > Theme & Logo page
5. Click on Export current theme
6. See exception
   

PrestaShop version(s) where the bug happened

1.7.7.8, 1.7.8.7, 8.0.0beta

PHP version(s) where the bug happened

7.2, 7.4

If your bug is related to a module, specify its name and its version

No response

[hibatallahAouadni]

Hello @khouloudbelguith

Thanks for reporting the issue!
I reproduce the issue with PS1786, see the attached screenshot below:

Thanks!

[matks]

As suggested above, instead of the page crashing we should have a red alert informing user that the language is not available

[HiCharly]

Hello

Here is a few questions to help determine the right way to proceed:

• In case of a not translated language, should we prevent the full theme export ? If yes, to export the theme, user will need to translate the missing language or delete it, right?
• What should be the message displayed yo the user ?
• Additional point : Would it be better to try to export only active languages ?