Fixes #68113: LinkedMap has extra keys sometimes

src/vs/base/common/map.ts

@@ -723,9 +723,21 @@ export class LinkedMap<K, V> {
 			this._tail = undefined;
 		}
 		else if (item === this._head) {
+			// This can only happend if size === 1 which is handle
+			// by the case above.
+			if (!item.next) {
+				throw new Error('Invalid list');
+			}
+			item.next.previous = undefined;
 			this._head = item.next;
 		}
 		else if (item === this._tail) {
+			// This can only happend if size === 1 which is handle
+			// by the case above.
+			if (!item.previous) {
+				throw new Error('Invalid list');
+			}
+			item.previous.next = undefined;
 			this._tail = item.previous;
 		}
 		else {
@@ -737,6 +749,8 @@ export class LinkedMap<K, V> {
 			next.previous = previous;
 			previous.next = next;
 		}
+		item.next = undefined;
+		item.previous = undefined;
 	}
 
 	private touch(item: Item<K, V>, touch: Touch): void {

src/vs/base/test/common/map.test.ts

@@ -226,6 +226,50 @@ suite('Map', () => {
 		});
 	});
 
+	test('LinkedMap - delete Head and Tail', function () {
+		const map = new LinkedMap<string, number>();
+
+		assert.equal(map.size, 0);
+
+		map.set('1', 1);
+		assert.equal(map.size, 1);
+		map.delete('1');
+		assert.equal(map.get('1'), undefined);
+		assert.equal(map.size, 0);
+		assert.equal(map.keys().length, 0);
+	});
+
+	test('LinkedMap - delete Head', function () {
+		const map = new LinkedMap<string, number>();
+
+		assert.equal(map.size, 0);
+
+		map.set('1', 1);
+		map.set('2', 2);
+		assert.equal(map.size, 2);
+		map.delete('1');
+		assert.equal(map.get('2'), 2);
+		assert.equal(map.size, 1);
+		assert.equal(map.keys().length, 1);
+		assert.equal(map.keys()[0], 2);
+	});
+
+	test('LinkedMap - delete Tail', function () {
+		const map = new LinkedMap<string, number>();
+
+		assert.equal(map.size, 0);
+
+		map.set('1', 1);
+		map.set('2', 2);
+		assert.equal(map.size, 2);
+		map.delete('2');
+		assert.equal(map.get('1'), 1);
+		assert.equal(map.size, 1);
+		assert.equal(map.keys().length, 1);
+		assert.equal(map.keys()[0], 1);
+	});
+
+
 	test('PathIterator', () => {
 		const iter = new PathIterator();
 		iter.reset('file:///usr/bin/file.txt');