If you get a Warning: Invalid argument supplied for foreach() but the code looks and seems to work fine then the issue is that foreach() needs an array but you are passing a Boolean due to an error in a previous function.

You will see this problem where you have something that is returning an array or false e.g. glob() and then you pass the returned value to the foreach() without checking if the variable isn’t false. e.g. in this case glob() can return false if it can’t see the path,

        foreach( $paths as $path ) {
            $filenames = glob( $path['path'] );
            if ( $filenames != false ) {
                foreach( $filenames as $filename )

In that example if glob() failed on one of the paths then it would return false. In my example above I check that $filenames is not false before I use it with foreach(). You can also use is_array() as well. To confirm your theory on your code you can add in var_dump() before the foreach() on the variable that you pass to confirm the type of the variable of what you use in foreach().