Use LESS to conditionally hide SL assets.

services/web/app/views/general/404.pug

@@ -4,12 +4,11 @@ block content
 	.content
 		.container
 			.error-container
-				if (settings.brandPrefix !== 'ol-')
-					.error-figure
-						img.error-img(
-							src="/img/brand/404-visual.svg"
-							alt="Not found"
-						)
+				.error-figure
+					img.error-img(
+						src="/img/brand/404-visual.svg"
+						alt="Not found"
+					)
 				.error-details
 					p.error-status Not found
 					p.error-description #{translate("cant_find_page")}

services/web/app/views/general/500.pug

@@ -10,12 +10,11 @@ html.full-height(itemscope, itemtype='http://schema.org/Product')
 		.content.full-height
 			.container.full-height
 				.error-container.full-height
-					if (settings.brandPrefix !== 'ol-')
-						.error-figure.error-figure-500
-							img.error-img(
-								src="/img/brand/500-visual-socket.svg"
-								alt="Error"
-							)
+					.error-figure.error-figure-500
+						img.error-img(
+							src="/img/brand/500-visual-socket.svg"
+							alt="Error"
+						)
 					.error-details
 						p.error-status Something went wrong, sorry.
 						p.error-description Our staff are probably looking into this, but if it continues, please contact us at #{settings.adminEmail}

services/web/public/stylesheets/app/error-pages.less

@@ -20,6 +20,11 @@
 			display: block;
 		}
 	}
+
+	.error-figure when (@is-overleaf = true) {
+		display: none;
+	}
+
 	.error-figure-500 {
 		&::before {
 			content: '';