Make sure the tooltip is not cut in half

[MAILPOET-3857]

assets/js/src/newsletters/send.jsx

@@ -548,7 +548,7 @@ class NewsletterSend extends React.Component {
             }
             { this.state.validationError !== undefined && (
               <HelpTooltip
-                tooltip={this.state.validationError}
+                tooltip={(<div>{this.state.validationError}</div>)}
                 tooltipId={this.state.validationError}
               />
             ) }