Undefined variable: body in Drupal\sendinblue\Tools\Http\SendinblueHttpClient->doRequest()

Problem/Motivation

In the doRequest method, if an exception is caught, the $body is not set and then a noticed is displayed.

Undefined variable: body in Drupal\sendinblue\Tools\Http\SendinblueHttpClient->doRequest()

Steps to reproduce

1. Create a form and place it on a page
2. Override the settings through settings.php to put a wrong key.
3. Go to the page that contains the form.

Proposed resolution

Return NULL after exception is caught.
Handle the missing data in getAttributes.

Have a good day.

Seb