Saving with empty Cache Location path does not default properly

[MarcGuay]

When you save the settings with an empty Cache Location, it does not default to WPSCSS_PLUGIN_DIR . '/cache/'.

I see two problems in class/class-wp-scss.php:

1. The isset check on line 167 (and 165 & 166 actually) do not work as expected because WordPress will store an empty string if text fields are empty, which will be evaluated as true, so the value of $cache_dir_setting will be an empty string and not WPSCSS_PLUGIN_DIR . '/cache/'.

2. On line 202 it is assumed that the cache dir will be prefixed in the base directory, which is not true for the default setting.

[MarcGuay]

For anyone struggling with this while the issue is still open, you'll need to enter a value in the Cache Location field. I use the Current Theme as my base dir and I am inputting /assets/wp-scss-cache/.