fix(portal): guard removeChild against externally cleared mount

packages/solid/web/src/index.ts

@@ -101,7 +101,7 @@ export function Portal<T extends boolean = false, S extends boolean = false>(pro
         insert(renderRoot, content);
         el.appendChild(container);
         props.ref && (props as any).ref(container);
-        onCleanup(() => el.removeChild(container));
+        onCleanup(() => el.contains(container) && el.removeChild(container));
       }
     },
     undefined,

packages/solid/web/test/portal.spec.tsx

@@ -115,6 +115,24 @@ describe("Testing a Portal with Synthetic Events", () => {
   test("dispose", () => disposer());
 });
 
+describe("Testing a Portal whose mount is externally cleared before disposal", () => {
+  let div = document.createElement("div"),
+    disposer: () => void;
+  const testMount = document.createElement("div");
+  const Component = () => <Portal mount={testMount}>Hi</Portal>;
+
+  test("Create portal", () => {
+    disposer = render(Component, div);
+    expect((testMount.firstChild as HTMLDivElement).innerHTML).toBe("Hi");
+  });
+
+  test("dispose does not throw when mount has been externally emptied", () => {
+    // Simulate an external actor clearing the mount node (e.g. innerHTML = "")
+    testMount.innerHTML = "";
+    expect(() => disposer()).not.toThrow();
+  });
+});
+
 describe("Testing a Portal with direct reactive children", () => {
   let div = document.createElement("div"),
     disposer: () => void,