Indeterminate paging - Previous page button fails to message source fn when initially loading last page [v4.12.x]

[pwpatton]

Describe the bug
indeterminate paging - previous page button fails to message source function when initially loading last paging

To Reproduce
Steps to reproduce the behavior:

1. In the example-paging-indeterminate-landmark.html in getDataPage change 'initial' req.type case to fall through to the 'last' req.type case.

       switch (request.type) {
          case 'first':   beginIndex = 0; break;
          case 'initial':   // <--- *NOTE*: Move 'initial' req.type to appear here and fall through to the last  req.type case.
          case 'last':    beginIndex = getData().length - request.pagesize; break;
          case 'next':    beginIndex = beginIndex + request.pagesize; break;
          case 'prev':    beginIndex = beginIndex - request.pagesize; break;

          case 'sorted':   console.log('sorted stub called - implement me'); break;
          case 'filtered': console.log('filtered stub called - implement me'); break;
        }

2. Go to http://localhost:4000/components/datagrid/example-paging-indeterminate-landmark.html
3. Click on previous page button
4. Notice no data changes and first and prev paging buttons become disabled.

Expected behavior
Previous button should message the source(reqType === 'previous') callback function.

Screenshots
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Platform

• PC
• Windows 10
• chrome

Additional context
Add any other context about the problem here.

[pwpatton]

Note, this all works fine unless you initially load the datagrid with the last page of records.

[tmcconechy]

Landmark requested this be patched back to 4.12.x

[clepore]

✅ Confirming to patch into 4.12.x

[tmcconechy]

This was patched and can be closed