Does not display a message “Done”

Hello.

Help solve the problem. Appointment works through time.
The user fills in all the fields and presses the “send” button.
The “Done” message does not always appear.
When it does not appear, a letter arrives, but it is impossible to confirm the record by reference. Below is the error from the log:

[16-Jun-2019 19:56:22 UTC] PHP Notice: Undefined index: captcha in /home/a0300681/domains/dr-lola.ru/public_html/wp-content/plugins/easy-appointments/src/ajax.php on line 1143
[16-Jun-2019 19:56:23 UTC] PHP Notice: Undefined index: ea_fields in /home/a0300681/domains/dr-lola.ru/public_html/wp-content/plugins/easy-appointments/src/fields/tablecolumns.php on line 91
[16-Jun-2019 19:56:23 UTC] PHP Notice: Undefined index: ea_fields in /home/a0300681/domains/dr-lola.ru/public_html/wp-content/plugins/easy-appointments/src/fields/tablecolumns.php on line 91
[16-Jun-2019 19:56:23 UTC] PHP Notice: Undefined index: ea_fields in /home/a0300681/domains/dr-lola.ru/public_html/wp-content/plugins/easy-appointments/src/fields/tablecolumns.php on line 91
[16-Jun-2019 19:56:23 UTC] PHP Notice: Undefined index: ea_fields in /home/a0300681/domains/dr-lola.ru/public_html/wp-content/plugins/easy-appointments/src/fields/tablecolumns.php on line 91
[16-Jun-2019 19:56:24 UTC] PHP Fatal error: Uncaught Google_Service_Exception: Error calling DELETE https://www.googleapis.com/calendar/v3/calendars/umj8ij8bqa0h7sh0u4p88fcfds%40group.calendar.google.com/events/rn4o8gke6k62pmluoa4q6q6u68: (410) Resource has been deleted in /home/a0300681/domains/dr-lola.ru/public_html/wp-content/plugins/easy-appointments-connect/vendor/google/apiclient/src/Google/Http/REST.php:110
Stack trace:
#0 /home/a0300681/domains/dr-lola.ru/public_html/wp-content/plugins/easy-appointments-connect/vendor/google/apiclient/src/Google/Http/REST.php(62): Google_Http_REST::decodeHttpResponse(Object(Google_Http_Request), Object(Google_Client))
#1 /home/a0300681/domains/dr-lola.ru/public_html/wp-content/plugins/easy-appointments-connect/vendor/google/apiclient/src/Google/Task/Runner.php(174): Google_Http_REST::doExecute(Object(Google_Client), Object(Google_Http_Request))
#2 /home/a0300681/domains/dr-lola.ru/public_html/wp-content/plugins/easy-appointments-connect/vendor/google/apiclient/src/Google/Http/REST.php(46): Google_Task_Runner->r in /home/a0300681/domains/dr-lola.ru/public_html/wp-content/plugins/easy-appointments-connect/vendor/google/apiclient/src/Google/Http/REST.php on line 110

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