Trouble logging in

Hello!

I am trying to log into my website on the admin side, and I keep getting the following message:

Warning: Creating default object from empty value in /home/customer/www/brittanyniehausphotography.ca/public_html/wp-content/plugins/flothemes-themeup/flothemes-themeup.php on line 140

Warning: Cannot modify header information - headers already sent by (output started at /home/customer/www/brittanyniehausphotography.ca/public_html/wp-content/plugins/flothemes-themeup/flothemes-themeup.php:140) in /home/customer/www/brittanyniehausphotography.ca/public_html/wp-includes/pluggable.php on line 1340

I tried resetting my password thinking that would help, but it didn’t and I keep getting the same message. Can someone please help me with this? My website is working when I go to it, I just can’t get into it to make changes.