Describe the bug

The "'Handles' story" is no longer working in the storybook demo.

Demo link: https://maxgraph.github.io/maxGraph/demo/?path=/story/layouts-handles--default

I do not know when this issue was introduced.

An error is displayed as an overlay and the story is not usable.

To Reproduce

Open the Handles demo page.

An error overlay appears and the story do not work.

Displayed error message: XMLSerializer.serializeToString: Argument 1 is not an object.

The issue occurs in both build and dev mode.

Stack trace displayed in the page (dev mode):

convertHtml @ SvgCanvas2D.js:745:39
createDiv @ SvgCanvas2D.js:763:37
text @ SvgCanvas2D.js:910:34
paint @ TextShape.js:179:15
redrawShape @ Shape.js:347:18
redraw @ Shape.js:250:18
redraw @ TextShape.js:207:19
redrawLabelShape @ CellRenderer.js:722:15
redrawLabel @ CellRenderer.js:667:22
redraw @ CellRenderer.js:1028:18
validateCellState @ GraphView.js:682:49
validate @ GraphView.js:448:58
graphModelChanged @ AbstractGraph.js:449:19
endUpdate @ GraphDataModel.js:961:25
batchUpdate @ AbstractGraph.js:412:29
Template @ Handles.stories.ts:115:9

Expected behavior

Handles should be displayed and usable, without any error overlay.

Environment

maxGraph version or commit: 7fe6793 (master branch cdedae6)

Browser: reproducible in current browsers

Mode: dev and build

Additional context

The issue seems related to SVG text or HTML serialization during label rendering.
No clear regression point identified yet.