Array to string conversion

This plugin show error when I install it. It says :

Array to string conversion in /…/../wp-content/plugins/tiled-gallery-carousel-without-jetpack/tiled-gallery.php on line 373

Then, I add this code

if ( isset( $img_meta['keywords'] ) ) {
			unset( $img_meta['keywords'] );
		}

just before this code..

$img_meta = json_encode( array_map( 'strval', $img_meta ) );

and that fix the problem ??

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