Avoid showing the message Page: 1 of 0 shown

[devdanzin]

In plone/Products.CMFPlone#3591, it's reported that the message Page: 1 of 0 shown is displayed when there are no pages. I think I've found the issue in mockup, here:

mockup/src/pat/structure/templates/paging.xml

Lines 46 to 51 in 51e2310

	<div class="pagination-info">
	<%- _t("Page:") %> <span class="current"><%- currentPage %></span>
	<%- _t("of") %>
	<span class="total"><%- totalPages %></span>
	<%- _t("shown") %>
	</div>

I think the fix should be here, checking that response.total is zero and setting this.state.totalPages to 1:

mockup/src/pat/structure/js/collections/result.js

Lines 70 to 73 in 51e2310

	parseState: function (response, queryParams, state, options) { // eslint-disable-line
	this.state.totalRecords = response.total;
	this.state.totalPages = Math.ceil(response.total / state.pageSize);
	},

Does this make sense? Should I send a PR?