Fix hydration-suspense crash due to sCU bailout

Assisted-By: devx/f79ddc2d-9f3b-44d1-85dc-4cb2c75c5ad5

Author: JoviDeCroock

compat/test/browser/suspense-hydration.test.jsx

@@ -348,6 +348,49 @@ describe('suspense hydration', () => {
 		});
 	});
 
+	it('does not crash when a hydrated suspended component bails out with shouldComponentUpdate', () => {
+		scratch.innerHTML = '<div>ssr</div>';
+		clearLog();
+
+		const promise = new Promise(() => {});
+		let update;
+
+		class Suspender extends React.Component {
+			shouldComponentUpdate() {
+				return false;
+			}
+
+			render() {
+				throw promise;
+			}
+		}
+
+		class App extends React.Component {
+			constructor(props) {
+				super(props);
+				this.state = { tick: 0 };
+				update = () => this.setState({ tick: this.state.tick + 1 });
+			}
+
+			render() {
+				return (
+					<Suspense fallback={<div>loading</div>}>
+						<Suspender tick={this.state.tick} />
+					</Suspense>
+				);
+			}
+		}
+
+		hydrate(<App />, scratch);
+		expect(scratch.innerHTML).to.equal('<div>ssr</div>');
+
+		update();
+		expect(() => rerender()).not.to.throw();
+		expect(scratch.innerHTML).to.equal('<div>ssr</div>');
+		expect(getLog()).to.deep.equal([]);
+		clearLog();
+	});
+
 	it('should leave DOM untouched when suspending while hydrating', () => {
 		scratch.innerHTML = '<!-- test --><div>Hello</div>';
 		clearLog();

src/diff/index.js

@@ -303,21 +303,20 @@ export function diff(
 						excessDomChildren[excessDomChildren.indexOf(oldDom)] = NULL;
 					}
 					newVNode._dom = oldDom;
-				} else {
-					if (excessDomChildren != NULL) {
-						for (let i = excessDomChildren.length; i--; ) {
-							removeNode(excessDomChildren[i]);
-						}
+				} else if (excessDomChildren != NULL) {
+					for (let i = excessDomChildren.length; i--; ) {
+						removeNode(excessDomChildren[i]);
 					}
-					markAsForce(newVNode);
 				}
 			} else {
 				newVNode._dom = oldVNode._dom;
-				if (!newVNode._children && oldVNode._children) {
-					newVNode._children = oldVNode._children;
-				}
-				if (!e.then) markAsForce(newVNode);
 			}
+
+			if (newVNode._children == NULL) {
+				newVNode._children = oldVNode._children || [];
+			}
+
+			if (!e.then) markAsForce(newVNode);
 			options._catchError(e, newVNode, oldVNode);
 		}
 	} else if (