docs/vendor.js
function assertReservedSlotInitialized(slotOffset, numSlots) {
    if (firstTemplatePass) {
        var startIndex = tView.bindingStartIndex - slotOffset;
        for (var i = 0; i < numSlots; i++) {
            assertEqual(viewData[startIndex + i], NO_CHANGE, 'The reserved slots should be set to `NO_CHANGE` on first template pass');
        }
    }
}
function assertReservedSlotInitialized(slotOffset, numSlots) {
    if (firstTemplatePass) {
        var startIndex = tView.bindingStartIndex - slotOffset;
        for (var i = 0; i < numSlots; i++) {
            assertEqual(viewData[startIndex + i], NO_CHANGE, 'The reserved slots should be set to `NO_CHANGE` on first template pass');
        }
    }
}
function assertReservedSlotInitialized ( slotOffset , numSlots ) { if ( firstTemplatePass ) { var startIndex = tView . bindingStartIndex - slotOffset ; for ( var i = 0 ; i < numSlots ; i ++ ) { assertEqual ( viewData [ startIndex + i ] , NO_CHANGE , 'The reserved slots should be set to `NO_CHANGE` on first template pass' ) ; } } }
On the first template pass, the reserved slots should be set `NO_CHANGE`.

If not, they might not have been actually reserved.
On the first template pass the reserved slots should be set NO_CHANGE .