I want to list the size of all sub-folders in a directory. when I try du -h --max-depth=1 the output is cluttered with 'Permission denied' statements as such

du: cannot read directory `./folder_name': Permission denied

How can I suppress these warnings?

I tried a workaround by piping the the output to grep as follows

du -h --max-depth=1 | grep -v 'du:'

but that does not seem to be working either!