[FIX] blockdom: undefined properties are treated as empty strings

src/blockdom/attributes.ts

@@ -139,7 +139,7 @@ export function updateClass(this: HTMLElement, val: any, oldVal: any) {
 
 export function makePropSetter(name: string): Setter<HTMLElement> {
   return function setProp(this: HTMLElement, value: any) {
-    (this as any)[name] = value;
+    (this as any)[name] = value || "";
   };
 }
 

tests/blockdom/block_attributes.test.ts

@@ -169,6 +169,15 @@ describe("properties", () => {
     expect(input.value).toBe("potato");
   });
 
+  test("input with value attribute, and undefined given", () => {
+    const block = createBlock(`<input block-attribute-0="value"/>`);
+
+    const tree = block([undefined]);
+    mount(tree, fixture);
+    const input = fixture.querySelector("input")!;
+    expect(input.value).toBe("");
+  });
+
   test("input type=checkbox with checked attribute", () => {
     // render input with initial value
     const block = createBlock(`<input type="checkbox" block-attribute-0="checked"/>`);

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

@@ -410,6 +410,24 @@ exports[`t-model directive on an textarea 1`] = `
 }"
 `;
 
+exports[`t-model directive t-model on an input with an undefined value 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { toNumber } = helpers;
+  
+  let block1 = createBlock(\`<input block-attribute-0=\\"value\\" block-handler-1=\\"input\\"/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const bExpr1 = ctx['state'];
+    const expr1 = 'text';
+    let attr1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
+    return block1([attr1, hdlr1]);
+  }
+}"
+`;
+
 exports[`t-model directive t-model on select with static options 1`] = `
 "function anonymous(bdom, helpers
 ) {

tests/components/t_model.test.ts

@@ -30,6 +30,19 @@ describe("t-model directive", () => {
     expect(fixture.innerHTML).toBe("<div><input><span>test</span></div>");
   });
 
+  test("t-model on an input with an undefined value", async () => {
+    class SomeComponent extends Component {
+      static template = xml`<input t-model="state.text"/>`;
+      state = useState({ text: undefined });
+    }
+    await mount(SomeComponent, fixture);
+
+    expect(fixture.innerHTML).toBe("<input>");
+
+    const input = fixture.querySelector("input")!;
+    expect(input.value).toBe("");
+  });
+
   test("basic use, on an input with bracket expression", async () => {
     class SomeComponent extends Component {
       static template = xml`