When trying to use a previously uploaded SVG via the default WordPress Image widget I get the following errors.
Warning: Illegal string offset 'width' in ../wp-includes/media.php on line 988
Warning: Illegal string offset 'height' in ../wp-includes/media.php on line 989
If I simply link to the same SVG via the default WordPress HTML widget using an < img src=”myfile.svg” / > then I don’t get an error.