Use get_file_size() in image edit view

wagtail/wagtailimages/views/images.py

@@ -118,21 +118,11 @@ def edit(request, image_id):
     except NoReverseMatch:
         url_generator_enabled = False
 
-    # Get file size
-    try:
-        filesize = image.file.size
-    except OSError:
-        # File doesn't exist
-        filesize = None
-        messages.error(request, _("The source image file could not be found. Please change the source or delete the image.").format(image.title), buttons=[
-            messages.button(reverse('wagtailimages_delete_image', args=(image.id,)), _('Delete'))
-        ])
-
     return render(request, "wagtailimages/images/edit.html", {
         'image': image,
         'form': form,
         'url_generator_enabled': url_generator_enabled,
-        'filesize': filesize,
+        'filesize': image.get_file_size(),
     })