Typos and race conditions.

weakermap/WeakerMap.mjs

@@ -1,8 +1,15 @@
 export class WeakerMap
 {
-	registry = new FinalizationRegistry(held => this.delete(held));
 	map = new Map;
 
+	registry = new FinalizationRegistry(key => {
+		if(this.map.has(key) && this.map.get(key).deref())
+		{
+			return;
+		}
+		this.delete(key);
+	});
+
 	constructor(entries)
 	{
 		entries && entries.forEach(([key, value]) => this.set(key, value));
@@ -75,7 +82,14 @@ export class WeakerMap
 			return;
 		}
 
-		return this.map.get(key).deref();
+		const value = this.map.get(key).deref();
+
+		if(!value)
+		{
+			this.map.delete(key);
+		}
+
+		return value;
 	}
 
 	has(key)
@@ -123,4 +137,4 @@ export class WeakerMap
 	}
 };
 
-Object.defineProperty(WeakerMap, Symbol.species, WeakerMap);
+Object.defineProperty(WeakerMap, Symbol.species, {value: WeakerMap});

weakerset/WeakerSet.mjs

@@ -133,4 +133,4 @@ export class WeakerSet
 	}
 };
 
-Object.defineProperty(WeakerMap, Symbol.species, WeakerMap);
+Object.defineProperty(WeakerSet, Symbol.species, {value: WeakerSet});