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Uncaught TypeError: Cannot read property 'clientWidth' of null

See original GitHub issue

I make a dynamic scrollbar to load users in my project, it will call serverice to get more users every time when I scroll to the bottom like below code block.

constructor(props) {
        super(props);

        this.state = {
            users: this.props.users ? [...this.props.users] : [],
            isBusy: true
        };
        this.lastScrollTop = 0;
        this.onScroll = this.onScroll.bind(this);
    }
onScroll(evt) {
        const scrollTop = evt.target.scrollTop;
        const clientHeight = evt.target.clientHeight;
        const scrollHeight = evt.target.scrollHeight;
        if (clientHeight + scrollTop === scrollHeight) {
            if (this.props.getUsers && this.hasNextPage) {
                this.lastScrollTop = scrollTop;
                this.props.getUsers(Id, this.pageIndex, this.state.searchText);
            }
        }
    }

And in componentWillReceiveProps I update the users in state

componentWillReceiveProps(nextProps) {
        if (this.props.users !== nextProps.users) {
            let users = this.state.usersAndGroups.concat(nextProps.usersAndGroups);
            this.setState({ users , isBusy: false });
        }
    }

Then in i will set the scrollbar to last scroll position

componentDidUpdate() {
        if (this.scrollbar) {
            this.scrollbar.scrollTop(this.lastScrollTop);
        }
    }

Then render it

<ScrollBar
                            style={{ width: '100%', height: '100%' }}
                            onScroll={this.onScroll}
                            ref={(scrollbar) => { this.scrollbar = scrollbar; }}>
                            <div>
                                {this.renderUserList(users)}
                            </div>
                        </ScrollBar>

All works well except it will throw below error in console when I scroll to the bottom to load next page users.

Uncaught TypeError: Cannot read property 'clientWidth' of null
at getInnerWidth
    at Scrollbars._update

And in the callstack is that el is null when get clientWidth el.clientWidth, anyone konw reason?

function getInnerWidth(el) {
                var clientWidth = el.clientWidth;

                var _getComputedStyle = getComputedStyle(el),
                    paddingLeft = _getComputedStyle.paddingLeft,
                    paddingRight = _getComputedStyle.paddingRight;

                return clientWidth - parseFloat(paddingLeft) - parseFloat(paddingRight);
            }`