fix: make sure close does not end early but killed does

Author: nbbeeken

src/cursor/abstract_cursor.ts

@@ -300,7 +300,11 @@ export abstract class AbstractCursor<
 
     try {
       while (true) {
-        if (this.closed) {
+        if (this.killed) {
+          return;
+        }
+
+        if (this.closed && this[kDocuments].length === 0) {
           return;
         }
 

test/integration/crud/misc_cursors.test.js

@@ -1870,7 +1870,7 @@ describe('Cursor', function () {
     const rejectedEarlyBecauseClientClosed = cursor.next().catch(error => error);
 
     await client.close();
-    expect(cursor).to.have.property('killed', true);
+    expect(cursor).to.have.property('closed', true);
 
     const error = await rejectedEarlyBecauseClientClosed;
     expect(error).to.be.instanceOf(MongoExpiredSessionError);