[FIX] fix some issues with t-out with falsy values, and with default value

tests/components/__snapshots__/basics.test.ts.snap

@@ -1308,6 +1308,18 @@ exports[`t-out in components can switch the contents of two t-out repeatedly 1`]
 }"
 `;
 
+exports[`t-out in components t-out and updating falsy values,  1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { safeOutput } = helpers;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return safeOutput(ctx['state'].a);
+  }
+}"
+`;
+
 exports[`t-out in components update properly on state changes 1`] = `
 "function anonymous(app, bdom, helpers
 ) {

tests/components/basics.test.ts

@@ -1084,4 +1084,25 @@ describe("t-out in components", () => {
     await nextTick();
     expect(fixture.innerHTML).toBe("<div>1</div><div>2</div>");
   });
+
+  test("t-out and updating falsy values, ", async () => {
+    class Test extends Component {
+      static template = xml`<t t-out="state.a"/>`;
+      state: any = useState({ a: 0 });
+    }
+
+    const comp = await mount(Test, fixture);
+    expect(fixture.innerHTML).toBe("0");
+    comp.state.a = undefined;
+    await nextTick();
+    expect(fixture.innerHTML).toBe("");
+
+    comp.state.a = "hello"
+    await nextTick();
+    expect(fixture.innerHTML).toBe("hello");
+
+    comp.state.a = false;
+    await nextTick();
+    expect(fixture.innerHTML).toBe("false");
+  });
 });