Garbage colleciton fix

src/manager.js

@@ -169,8 +169,12 @@ export class ZimManager {
 				pending = new ZimReader(file, {clusterTTL: this.#clusterTTL}).open();
 				this.#opening.set(file, pending);
 			}
-			const reader = await pending;
-			this.#opening.delete(file);
+			let reader;
+			try {
+				reader = await pending;
+			} finally {
+				this.#opening.delete(file);
+			}
 			entry = this.#readers.get(file) ?? {reader};
 			this.#readers.set(file, entry);
 		}

src/reader.js

@@ -294,8 +294,14 @@ export class ZimReader {
 	/** Opens the archive and parses its header + mimetype list. */
 	async open() {
 		this.#fd = await fs.promises.open(this.path, 'r');
-		await this.#readHeader();
-		await this.#readMimeTypes();
+		try {
+			await this.#readHeader();
+			await this.#readMimeTypes();
+		} catch (e) {
+			await this.#fd.close();
+			this.#fd = null;
+			throw e;
+		}
 		return this;
 	}