[WIN32K] Fix missing NULL check in NtGdiPathToRegion

win32ss/gdi/ntgdi/path.c

@@ -2893,6 +2893,14 @@ NtGdiPathToRegion(HDC  hDC)
         hrgnRval = Rgn->BaseObject.hHmgr;
 
         pNewPath = PATH_FlattenPath(pPath);
+        if (pNewPath == NULL)
+        {
+            ERR("Failed to flatten path %p\n", pDc->dclevel.hPath);
+            REGION_Delete(Rgn);
+            PATH_UnlockPath(pPath);
+            DC_UnlockDc(pDc);
+            return NULL;
+        }
 
         Ret = PATH_PathToRegion(pNewPath, pdcattr->jFillMode, Rgn);