Generates compiled file on root directory when set compiled path doesn't exists

[skys215]

I cloned a lumen-based project and changed my storage path.
When I visit the homepage, it comes out with the error:

ErrorException in Filesystem.php line 81:
file_put_contents(/f536123a25b04be16752e137caae936b): failed to open stream: Permission denied

It's quite weird that cache file is going to store at root directory. I didn't set that kind of thing.
After debugging, I found out that the problem comes from config/view.php#L31.
According to the PHP Document of realpath function, it will return false when the directory doesn't exists, which will be convert to empty string "" when generating the compiled path at View/Compilers/Compiler.php#44.
I think the compiled path should be created when the application starts or it's better to dump more friendly message rather then compiling on the root directory.

[GrahamCampbell]

Thanks for the report.

[GrahamCampbell]

See #14277.