✨ Saving image relations on save in editor

frontend/src/lib/editor/card.svelte

@@ -110,7 +110,7 @@
 								class="rounded-full absolute -top-2 -right-2 opacity-70 hover:opacity-100 transition"
 								type="button"
 								on:click={() => {
-									data.questions[selected_question].image = '';
+									data.questions[selected_question].image = null;
 								}}
 							>
 								<svg

frontend/src/lib/editor/settings-card.svelte

@@ -72,7 +72,7 @@
 						alt="not available"
 						class="max-h-72 h-auto w-auto"
 						on:contextmenu|preventDefault={() => {
-							data.cover_image = '';
+							data.cover_image = null;
 						}}
 					/>
 				</div>