I confirm. SVG files should be bypassed in get_image_metadata_alttext function.
@Turtle91: If you need a quick workaround then change a tiny bit in the code (line 484) in the plugin.py file.
Code:
if not alttext or alttext=='':
if not imgpath.lower().endswith('.svg'):
alttext = get_image_metadata_alttext(imgpath, plang)
Surely KevinH will do better soon