fix: stylesheet loading

src/mergeHeadContents.ts

@@ -19,15 +19,18 @@ export default function mergeHeadContents(
 		.forEach(({ el }) => currentHead.removeChild(el));
 
 	// Insert tag *after* previous version of itself to preserve JS variable scope and CSS cascade
-	addTags
+	const newAddTags = addTags
 		.filter(({ el }) => shouldManageTag(el))
-		.forEach(({ el, index = 0 }) => {
-			currentHead.insertBefore(el.cloneNode(true), currentHead.children[index + 1] || null);
+		.map((tag) => {
+			let newEl = tag.el.cloneNode(true) as Element;
+			currentHead.insertBefore(newEl, currentHead.children[(tag.index || 0) + 1] || null);
+
+			return { ...tag, el: newEl };
 		});
 
 	return {
 		removed: removeTags.map(({ el }) => el),
-		added: addTags.map(({ el }) => el)
+		added: newAddTags.map(({ el }) => el)
 	};
 }
 

src/waitForAssets.ts

@@ -13,18 +13,23 @@ export function waitForStylesheet(
 	element: HTMLLinkElement,
 	timeoutMs: number = 0
 ): Promise<HTMLLinkElement> {
+	let timeoutId: ReturnType<typeof setTimeout>;
+
 	const whenLoaded = (cb: () => void) => {
 		if (element.sheet) {
 			cb();
 		} else {
-			setTimeout(() => whenLoaded(cb), 10);
+			timeoutId = setTimeout(() => whenLoaded(cb), 10);
 		}
 	};
 
 	return new Promise((resolve) => {
 		whenLoaded(() => resolve(element));
 		if (timeoutMs > 0) {
-			setTimeout(() => resolve(element), timeoutMs);
+			setTimeout(() => {
+				if (timeoutId) clearTimeout(timeoutId);
+				resolve(element);
+			}, timeoutMs);
 		}
 	});
 }