Found this while researching this comment: #64971 (comment)

What?

This PR fixes a critical error that occurs when null is passed to the values ​​prop of the BoxControl component.

The only time this error can occur in Gutenberg project is if the following conditions are met:

• The active theme is a block theme
• The theme supports blockGap (settings.appearanceTools is true or settings/spacing.blockGap is true)
• There is no spacing preset
• Access blocks with axial gap support via the global styles (e.g. Columns block)

Uncaught TypeError: Cannot convert undefined or null to object
    at Function.values (<anonymous>)
    at isValuesDefined (utils.ts:183:10)
    at BoxControl (index.tsx:93:41)
    at renderWithHooks (react-dom.js?ver=18:15496:20)
    at mountIndeterminateComponent (react-dom.js?ver=18:20113:15)
    at beginWork (react-dom.js?ver=18:21636:18)
    at HTMLUnknownElement.callCallback (react-dom.js?ver=18:4151:16)
    at Object.invokeGuardedCallbackDev (react-dom.js?ver=18:4200:18)
    at invokeGuardedCallback (react-dom.js?ver=18:4264:33)
    at beginWork$1 (react-dom.js?ver=18:27500:9)

Why?

If the theme does not have a spacing preset and the block supports the axial gap, the block spacing UI will be rendered as a BoxControl component here:

Moreover, the initial value of the block gap is null, which is passed as the value of the values ​​prop here.

As a result, a critical error occurs in the isValuesDefined() function when Object.values( null ).filter is executed:

How?

Perhaps the ideal solution would be to investigate why the initial value of the blockGap is null and convert it to undefined. However, the SpacingSizesControl component also has the isValuesDefined() function, which checks for null in addition to undefined:

Therefore, it seems better to add a null check to the BoxControl component itself as well.

Testing Instructions

• Activate the Emptytheme and update theme.json as follows:

  {
  	"version": 3,
  	"settings": {
  		"appearanceTools": true,
  		"layout": {
  			"contentSize": "840px"
  		},
  		"spacing": {
  			"spacingSizes": [],
  			"defaultSpacingSizes": false
  		}
  	}
  }

• Access the Site Editor > Global styles > Blocks > Columns
  • trunk: The critical error occurs.
  • This PR: The critical error does not occur and the block spacing UI is rendered.