Normalizes the user destination option.
If disabled ("none") or not provided, the result will be the empty string.
If local (even if file://), the result will be a resolved absolute path.
If the local location does not exist or is not a dir, an assert is thrown.
If a non-file URL, the destination will be returned as-is.
Normalizes the user destination option. If disabled ("none") or not provided, the result will be the empty string. If local (even if file://), the result will be a resolved absolute path.