implemet fix for PLT-2606 (#6238)

webapp/components/invite_member_modal.jsx

@@ -115,22 +115,21 @@ class InviteMemberModal extends React.Component {
         var valid = true;
 
         for (var i = 0; i < count; i++) {
-            var index = inviteIds[i];
             var invite = {};
+            var index = inviteIds[i];
             invite.email = ReactDOM.findDOMNode(this.refs['email' + index]).value.trim();
+            invite.firstName = ReactDOM.findDOMNode(this.refs['first_name' + index]).value.trim();
+            invite.lastName = ReactDOM.findDOMNode(this.refs['last_name' + index]).value.trim();
+            if (invite.email !== '' || index === 0) {
                 if (!invite.email || !utils.isEmail(invite.email)) {
                     emailErrors[index] = this.props.intl.formatMessage(holders.emailError);
                     valid = false;
                 } else {
                     emailErrors[index] = '';
                 }
-
-            invite.firstName = ReactDOM.findDOMNode(this.refs['first_name' + index]).value.trim();
-
-            invite.lastName = ReactDOM.findDOMNode(this.refs['last_name' + index]).value.trim();
-
                 invites.push(invite);
             }
+        }
 
         this.setState({emailErrors, firstNameErrors, lastNameErrors});