Fix node component slotting

Author: kai

src/NodeComponent.ts

@@ -76,14 +76,13 @@ export abstract class NodeComponent<T extends Node> {
 
 	/**
 	 * Render this component in the place of a `<slot name="…"></slot>`.
-	 * If multiple slots with the same name are found, they will all be used.
 	 * @param slot The slot name
 	 * @param [parent] The parent element within to search for slots. Defaults to `document`
 	 */
 	public slot(slot: string, parent: ParentNode = document) {
-		const slotNodes = parent.querySelectorAll(`slot[name="${slot}"]`);
-		for (const slotNode of slotNodes)
-			slotNode.replaceWith(this.node);
+		const slotNode = parent.querySelector(`slot[name="${slot}"]`);
+		if (slotNode == null) throw new DOMException(`NodeComponent.slot: Could not find slot ${slot}`);
+		slotNode.replaceWith(this.node);
 		return this;
 	}
 }