Font Library doesn't support Font Faces that have multiple assets.

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Description

If a user installs a font face from a Font collection that references an ARRAY of sources the front-end throws an error and doesn't add the font face.

If the font face src is a STRING then the installation works as expected.
If the font face src is an ARRAY of strings (which is valid) the front-end will throw an error.

Step-by-step reproduction instructions

Add a Font Collection that has a font face that references multiple font faces like so:

wp_register_font_collection( array(
	'slug'        => 'test-collection',
	'name'        => 'Test Collection',
	'description' => 'A Font Collection to use to break stuff.',
	'font_families'        => array( [
    		'font_family_settings' => array(
    			'name'       => 'Test Font Family',
    			'fontFamily' => 'Test Font Family',
    			'slug'       => 'test-font-family',
    			'fontFace'   => array( array(
          			'src'        => [
					'https://fonts.gstatic.com/s/texturina/v28/c4mM1nxpEtL3pXiAulRTkY-HGmNEX1b9NspjMwhAgliHhVrXy2eYGvUg25riW1OD.ttf',
                			'https://fonts.gstatic.com/s/chivo/v18/va9b4kzIxd1KFppkaRKvDRPJVDf_vB_ul2DSFXjQiQ.ttf',
				],
            			'fontWeight' => '400',
            			'fontStyle'  => 'normal',
            			'fontFamily' => 'Test Font Family',
        		) ),
		),
	], ),
) );

Screenshots, screen recording, code snippet

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Environment info

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Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes