fix: add more checks around cached rows (#880)

- there were many assumptions that certain objects/fields were defined and calls on them were being made but it could happen in certain rare case that these row cache fields are actually undefined and that threw errors on our end, so this PR adds more checks before using any of these row cache objects/arrays

Author: ghiscoding

slick.grid.js

@@ -3981,7 +3981,7 @@ if (typeof Slick === "undefined") {
     function ensureCellNodesInRowsCache(row) {
       const cacheEntry = rowsCache[row];
       if (cacheEntry) {
-        if (cacheEntry.cellRenderQueue.length) {
+        if (cacheEntry.cellRenderQueue.length && cacheEntry.rowNode && cacheEntry.rowNode.length) {
           const rowNode = cacheEntry.rowNode;
           let children = Array.from(rowNode[0].children);
           if (rowNode.length > 1) {
@@ -4194,20 +4194,28 @@ if (typeof Slick === "undefined") {
       for (var i = 0, ii = rows.length; i < ii; i++) {
         if (( hasFrozenRows ) && ( rows[i] >= actualFrozenRow )) {
             if (hasFrozenColumns()) {
+              if (rowsCache && rowsCache.hasOwnProperty(rows[i]) && x.firstChild && xRight.firstChild) {
                 rowsCache[rows[i]].rowNode = [x.firstChild, xRight.firstChild];
                 _canvasBottomL.appendChild(x.firstChild);
                 _canvasBottomR.appendChild(xRight.firstChild);
+              }
             } else {
+              if (rowsCache && rowsCache.hasOwnProperty(rows[i]) && x.firstChild) {
                 rowsCache[rows[i]].rowNode = [x.firstChild];
                 _canvasBottomL.appendChild(x.firstChild);
+              }
             }
         } else if (hasFrozenColumns()) {
+          if (rowsCache && rowsCache.hasOwnProperty(rows[i]) && x.firstChild && xRight.firstChild) {
             rowsCache[rows[i]].rowNode = [x.firstChild, xRight.firstChild];
             _canvasTopL.appendChild(x.firstChild);
             _canvasTopR.appendChild(xRight.firstChild);
+          }
         } else {
+          if (rowsCache && rowsCache.hasOwnProperty(rows[i]) && x.firstChild) {
             rowsCache[rows[i]].rowNode = [x.firstChild];
             _canvasTopL.appendChild(x.firstChild);
+          }
         }
       }