fix: Remove object from cache (#6257)

Author: Jason3S

packages/flatpack-json/src/Flatpack.mts

@@ -599,6 +599,24 @@ export class FlatpackStore {
         assigned.set(this.refUndefined, 0);
         calcAvailableIndexes();
         addElements(this.root);
+        this.#cleanCache();
+    }
+
+    /**
+     * Remove objects from the cache after the FlatpackStore has been built.
+     */
+    #cleanCache() {
+        const toRemove = new Set<unknown>();
+
+        for (const key of this.cache.keys()) {
+            if (key && typeof key === 'object') {
+                toRemove.add(key);
+            }
+        }
+
+        for (const key of toRemove) {
+            this.cache.delete(key);
+        }
     }
 
     toJSON(): Flatpacked {

packages/flatpack-json/src/Flatpack.test.mts

@@ -177,6 +177,18 @@ describe('Flatpack', async () => {
         const s2 = fp.stringify();
         expect(s2).toEqual(s1);
     });
+
+    test('Updating the object used.', () => {
+        const data: Record<string, number | string | number[]> & { d: number[] } = { a: 1, b: 2, d: [1, 2, 3] };
+        const fp = new FlatpackStore(data);
+        const v = fp.toJSON();
+        expect(fromJSON(v)).toEqual(data);
+        data.c = 3;
+        data.d.push(4);
+        fp.setValue(data);
+        expect(fromJSON(fp.toJSON())).toEqual(data);
+        expect(fp.toJSON()).not.toEqual(v);
+    });
 });
 
 async function sampleFileList() {