fix(app): guard reentrant Solid cleanup (#39261)

Co-authored-by: Jack <jack@anoma.ly>

packages/app/test-browser/solid-router-cleanup.test.ts

@@ -0,0 +1,64 @@
+import { expect, test } from "bun:test"
+import { MetaProvider, Title } from "@solidjs/meta"
+import { MemoryRouter, Route, createMemoryHistory, useParams } from "@solidjs/router"
+import { createMemo } from "solid-js"
+import { createComponent, render } from "solid-js/web"
+
+test("route cleanup cannot invalidate an owner list being disposed", async () => {
+  const host = document.createElement("div")
+  document.body.append(host)
+  const history = createMemoryHistory()
+
+  const RepoPage = () => {
+    const params = useParams<{ id?: string }>()
+    const title = createMemo(() => params.id ?? "")
+    const button = document.createElement("button")
+    button.textContent = "Back"
+    button.addEventListener("click", () => history.set({ value: "/", scroll: false, replace: false }))
+    return [
+      createComponent(Title, {
+        get children() {
+          return title()
+        },
+      }),
+      button,
+    ]
+  }
+
+  const HomePage = () => {
+    const button = document.createElement("button")
+    button.textContent = "Go"
+    button.addEventListener("click", () => history.set({ value: "/project", scroll: false, replace: false }))
+    return button
+  }
+
+  const App = () =>
+    createComponent(MetaProvider, {
+      get children() {
+        return createComponent(MemoryRouter, {
+          history,
+          get children() {
+            return [
+              createComponent(Route, { path: "/", component: HomePage }),
+              createComponent(Route, { path: "/:id", component: RepoPage }),
+            ]
+          },
+        })
+      },
+    })
+
+  const dispose = render(() => createComponent(App, {}), host)
+  const go = host.querySelector("button")
+  expect(go?.textContent).toBe("Go")
+  go?.click()
+  await new Promise((resolve) => setTimeout(resolve, 0))
+
+  const back = host.querySelector("button")
+  expect(back?.textContent).toBe("Back")
+  back?.click()
+  await new Promise((resolve) => setTimeout(resolve, 0))
+
+  expect(host.querySelector("button")?.textContent).toBe("Go")
+  dispose()
+  host.remove()
+})