Fix CacheMap when cache is corrupted

[villfa]

Hi,

The goal of this PR is to prevent errors of this sort:

TypeError: Cannot assign null to property Backpack\Basset\Helpers\CacheMap::$map of type array

/vendor/backpack/basset/src/Helpers/CacheMap.php:31
/vendor/backpack/basset/src/BassetManager.php:45
/vendor/backpack/basset/src/BassetServiceProvider.php:72
/vendor/laravel/framework/src/Illuminate/Container/Container.php:952
/vendor/laravel/framework/src/Illuminate/Container/Container.php:832
/vendor/laravel/framework/src/Illuminate/Foundation/Application.php:1078
/vendor/laravel/framework/src/Illuminate/Container/Container.php:763
/vendor/laravel/framework/src/Illuminate/Foundation/Application.php:1058
/vendor/laravel/framework/src/Illuminate/Container/Container.php:1580
/vendor/laravel/framework/src/Illuminate/Support/Facades/Facade.php:239
/vendor/laravel/framework/src/Illuminate/Support/Facades/Facade.php:210
/vendor/laravel/framework/src/Illuminate/Support/Facades/Facade.php:355
/vendor/backpack/crud/src/BackpackServiceProvider.php:65
[...]

I observed this error in very rare occasions so I'm not sure how to reproduce.

[pxpm]

Thanks @villfa !

I agree we can gracefully handle the corrupt map files. Since we are changing it, I am tempted to use a more fool proof to handle other generic errors that might happen with the file read.

What you think ? Willing to do the changes in the PR ?

Cheers

[villfa]

BTW, would it be possible to cherry-pick this change and make a 1.3.10 release?

I won't be able to migrate to Backpack v7 for a few months, so it would be great to benefit from this fix in the meantime.