fix(cli): say a font or image URL is a download, not a page, when capture is given one (#6952)

* fix(cli): say a font or image URL is a download, not a page, when capture is given one

* fix(cli): word the capture download hint as a likely cause, not a fact

packages/cli/src/capture/navigateForCapture.test.ts

@@ -545,6 +545,17 @@ describe("a proxy that was in the way", () => {
     );
   });
 
+  it("tells a file URL apart from a page when the browser turns it into a download", async () => {
+    const goto = vi
+      .fn()
+      .mockRejectedValue(new Error("net::ERR_ABORTED at https://cdn.example/arabic.woff2"));
+    await expect(
+      navigateForCapture({ goto }, "https://cdn.example/arabic.woff2", 120_000),
+    ).rejects.toThrow(
+      /cdn\.example stopped loading as a page.*file download such as a font.*assets\/fonts.*net::ERR_ABORTED/,
+    );
+  });
+
   it("leaves every other failure as it was", async () => {
     const name = new Error("net::ERR_NAME_NOT_RESOLVED at https://nope.example/");
     expect(explainProxyRefusal(name, "https://nope.example/")).toBe(name);

packages/cli/src/capture/navigateForCapture.ts

@@ -16,6 +16,8 @@ const PROXY_FAILURES = {
     `Your network's proxy refused the connection to ${host}. Ask whoever runs it to allow ${host}.`,
   "net::ERR_PROXY_CONNECTION_FAILED": () =>
     "Could not reach your network's proxy. Check the proxy address and that the proxy is running, or ask whoever runs it.",
+  "net::ERR_ABORTED": (host: string) =>
+    `${host} stopped loading as a page. This usually means the URL is a file download such as a font, not a web page. Capture a page that uses the file; its fonts are saved to assets/fonts.`,
 } as const;
 const PROXY_FAILURE = new RegExp(Object.keys(PROXY_FAILURES).join("|"));