grid.load() regression in v12.4.x — widgets without explicit h property all stack at (0,0), gs-current-row="NaN"

[vukadinFE]

Describe the bug

After upgrading from 12.3.3 to 12.4.2, all widgets loaded via grid.load() stack on top of each other at position (0, 0). The grid container shows gs-current-row="NaN" and every item gets gs-x="0" gs-y="0".

The issue appears to be caused by widgets that omit the h (height) property. In 12.3.3, h defaults to 1 implicitly. In 12.4.x, the missing h causes row calculation to produce NaN, breaking the entire layout.

To Reproduce

const grid = GridStack.init({
  float: false,
  cellHeight: 292,
  minRow: 1,
  margin: "8px",
  column: 2,
  disableResize: true,
});

// Widgets WITHOUT explicit `h` property
grid.load([
  { type: "widget-A", w: 2, x: 0, y: 0 },
  { type: "widget-B", w: 1, x: 0, y: 1 },
  { type: "widget-C", w: 1, x: 1, y: 1 },
  { type: "widget-D", w: 2, x: 0, y: 2 },
]);

Expected behavior

Widgets should default to h: 1 when h is not provided (as in 12.3.3), and layout correctly based on their x/y values.

Actual behavior

All widgets render at (0, 0) overlapping each other. Inspecting the DOM:

v12.3.3 (working):

<div class="grid-stack" gs-current-row="4" style="--gs-cell-height: 292px; --gs-column-width: 50%;">
  <div class="grid-stack-item" gs-x="0" gs-y="0" gs-w="2" style="width: calc(2 * var(--gs-column-width));">
  <div class="grid-stack-item" gs-x="0" gs-y="1" gs-w="1" style="top: var(--gs-cell-height); left: var(--gs-column-width);">
  ...
</div>

v12.4.2 (broken):

<div class="grid-stack" gs-current-row="NaN" style="--gs-cell-height: 292px; --gs-column-width: 50%;">
  <div class="grid-stack-item" gs-x="0" gs-y="0" gs-w="2" style="width: calc(2 * var(--gs-column-width));">
  <div class="grid-stack-item" gs-x="0" gs-y="0" gs-w="2" style="width: calc(2 * var(--gs-column-width));">
  ...
</div>

Workaround

Explicitly adding h: 1 to every widget before calling load() fixes the issue:

grid.load(widgets.map(w => ({ ...w, h: 1 })));

Environment

• gridstack version: 12.4.2 (works on 12.3.3)
• Browser: Chrome (latest)
• Framework: Vue 3 (using GridStack.renderCB)
• Build tool: Vite (issue occurs in production builds; dev mode also affected)

Additional context

The regression was likely introduced by a change in load() or the engine's layout calculation between 12.3.3 and 12.4.0. Previously, missing h was implicitly treated as 1. Now it seems to propagate as undefined/NaN through the row height calculation, causing gs-current-row="NaN" on the container.

[adumesny]

@vukadinFE not seeing the issue with latest 12.6.0 build. I copied your code to float.html demo and looks right.