there still one more location where size comes out to be undef due to circular/unresolved symbolic link which i could not locate

Well, i do see the problem now; it would happen while calculating the size of $path in the alternate branch ...

if ( -d $path && !-l $path ) {
...
}
else {
            my $fileSize = -s $path;
            ...
            $sizeTotal += $fileSize;
}
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The -s function causes chase of symlink via stat which brings back unresolved link which gives undef to $fileSize. So when undef is added to $sizeTotal, we get the previously mentioned "uninitialized" error message.