Trying to create custom default avatars

Can I get help with this? https://premium.wpmudev.org/blog/how-to-add-a-custom-default-avatar-for-buddypress-members-and-groups/ been trying to make this work but I keep getting errors. A blank functions.php files is placed in blogs-mu-child folder with the following (attached)

I keep getting the error below when a user tries to create a new group.

Warning: Cannot modify header information - headers already sent by (output started at /home2/maindomain/public_html/wpmudomain/wp-content/themes/blogs-mu-child/functions.php:10) in /home2/maindomain/public_html/wpmudomain/wp-content/plugins/buddypress/bp-groups.php on line 1118

Warning: Cannot modify header information - headers already sent by (output started at /home2/maindomain/public_html/wpmudomain/wp-content/themes/blogs-mu-child/functions.php:10) in /home2/maindomain/public_html/wpmudomain/wp-content/plugins/buddypress/bp-groups.php on line 1119

Warning: Cannot modify header information - headers already sent by (output started at /home2/maindomain/public_html/wpmudomain/wp-content/themes/blogs-mu-child/functions.php:10) in /home2/maindomain/public_html/wpmudomain/wp-includes/pluggable.php on line 890

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