Errors when installing

When I installed your plugin I received the following error and warning:

Cannot send session cache limiter – headers already sent (output started at /home/name/public_html/site.com/wp-content/plugins/search-keyword-statistics/admin.php:80) in /home/name/public_html/site.com/wp-content/plugins/custom-sidebars/inc/class-custom-sidebars-explain.php on line 55

The plugin generated 4 characters of unexpected output during activation. If you notice “headers already sent” messages, problems with syndication feeds or other issues, try deactivating or removing this plugin.

I expect the first has to do with the other plugin, on this I will check, but the second seems to be specifically about your plugin. When I refreshed the admin page the second warning disappears. Could one be related to the other? How can this be fixed?

https://ww.wp.xz.cn/plugins/search-keyword-statistics/