Error message

• Notice: Trying to access array offset on value of type bool in simplenews_newsletter_defaults() (line 456 of /homepages/41/d237307506/htdocs/lll/sites/all/modules/simplenews/simplenews.module).
• Notice: Trying to access array offset on value of type null in simplenews_newsletter_defaults() (line 456 of /homepages/41/d237307506/htdocs/lll/sites/all/modules/simplenews/simplenews.module).