Fix: Make sizeBasis optional in IconLayer type definition

[Copilot]

Closes #9851

Background

The sizeBasis property was added in #9736 with a default value of 'height' but incorrectly marked as required in the TypeScript type definition, causing type errors when the property is omitted:

// This should work but throws: Property 'sizeBasis' is missing in type
new IconLayer({
  id: 'icons',
  data: [],
  getPosition: d => d.coordinates,
  getIcon: d => 'marker'
});

Change List

• Mark sizeBasis as optional in _IconLayerProps<DataT> type definition to align with its default value and documentation

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Original prompt

---

This section details on the original issue you should resolve

<issue_title>[Bug] Unnecessarily required properties: sizeBasis</issue_title>
<issue_description>### Description

#9736

The sizeBasis property was newly added in the above PR, but according to the documentation committed alongside it, this property is optional.

Actually this property is required in the type definition, resulting in a type error as shown in the attached image.

Flavors

• Script tag
• React
• Python/Jupyter notebook
• MapboxOverlay
• GoogleMapsOverlay
• CARTO
• ArcGIS

Expected Behavior

No response

Steps to Reproduce

When using IconLayer in TypeScript without the sizeBasis property.

Environment

• Framework version: deck.gl@9.2.2
• Browser: -
• OS: -

Logs

No response</issue_description>

<agent_instructions>Please mark the sizeBasis prop as optional in the IconLayer</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes [Bug] Unnecessarily required properties: sizeBasis #9882

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Note

Marks IconLayer prop sizeBasis as optional to align with defaults and prevent TypeScript errors when omitted.

^{Written by Cursor Bugbot for commit 1ae1c50. This will update automatically on new commits. Configure here.}

[coveralls]

coverage: 91.144%. remained the same
when pulling 1ae1c50 on copilot/fix-size-basis-type-error
into f713242 on master.