add test

packages/@ember/-internals/metal/lib/computed.ts

@@ -541,6 +541,8 @@ export class ComputedProperty extends ComputedDescriptor {
     let ret;
 
     if (EMBER_METAL_TRACKED_PROPERTIES) {
+      // For backwards compatibility, we only throw if the CP has any dependencies. CPs without dependencies
+      // should be allowed, even after the object has been destroyed, which is why we check _dependentKeys.
       assert(
         `Attempted to access the computed ${obj}.${keyName} on a destroyed object, which is not allowed`,
         this._dependentKeys === undefined || !metaFor(obj).isMetaDestroyed()

packages/@ember/-internals/metal/tests/computed_test.js

@@ -604,6 +604,23 @@ moduleFor(
 
       expectAssertion(() => get(obj, 'foo'), message);
     }
+
+    ['@test does not throw an assertion if an uncached `get` is called on computed without dependencies after object is destroyed'](
+      assert
+    ) {
+      let meta = metaFor(obj);
+      defineProperty(
+        obj,
+        'foo',
+        computed(function() {
+          return 'baz';
+        })
+      );
+
+      meta.destroy();
+
+      assert.equal(get(obj, 'foo'), 'baz', 'CP calculated successfully');
+    }
   }
 );