Fix: Add missing await to fromDataBuffer call in font upload

[GovardhaneNitin]

The fromDataBuffer method is async but was being called without await, causing a race condition that resulted in 'Invalid font data in ArrayBuffer' errors when uploading TTF fonts.

This fix ensures the font parsing completes before proceeding with metadata extraction, resolving the issue where TTF fonts would fail to upload while WOFF2 files worked correctly.

Fixes #72265

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[Copilot]

Pull request overview

This PR adds the missing await keyword when calling the async fromDataBuffer method during font upload, and updates the TypeScript type definition to reflect that fromDataBuffer returns a Promise<void>. The change aims to fix a race condition that caused "Invalid font data in ArrayBuffer" errors when uploading TTF fonts.

• Updated the return type of fromDataBuffer in the type definition from void to Promise<void>
• Added await when calling fontObj.fromDataBuffer() in the font metadata extraction function

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated no comments.

File	Description
packages/global-styles-ui/src/font-library-modal/lib/lib-font.browser.d.ts	Updates the TypeScript type definition to correctly indicate that fromDataBuffer returns a Promise
packages/global-styles-ui/src/font-library-modal/upload-fonts.tsx	Adds await to the fromDataBuffer call to properly wait for font parsing to complete

Comments suppressed due to low confidence (1)

packages/global-styles-ui/src/font-library-modal/upload-fonts.tsx:159

• Adding await here creates a race condition. The fromDataBuffer method calls this.onload(evt) at the end of its execution (line 847 in lib-font.browser.js). By awaiting this call, fromDataBuffer completes before the onload handler is set up on line 158 below. This means the onload callback is invoked when fontObj.onload is still undefined, so the Promise on lines 157-159 will never resolve, causing the code to hang.

The solution is to set up the onload handler BEFORE calling fromDataBuffer, or remove the redundant Promise wait on lines 157-159 since fromDataBuffer is now properly awaited and the font data will be available after line 155 completes.

		await fontObj.fromDataBuffer( buffer, fontFile.name );
		// Assuming that fromDataBuffer triggers onload event and returning a Promise
		const onloadEvent: { detail: { font: any } } = await new Promise(
			( resolve ) => ( fontObj.onload = resolve )
		);

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