fix(shadcn): surface network failure reason from fetch errors

packages/shadcn/src/registry/proxy.ts

@@ -11,11 +11,44 @@ const proxyDispatcher =
     ? new EnvHttpProxyAgent()
     : undefined
 
-export function fetchWithProxy(url: string | URL, init?: RequestInit) {
-  // The `dispatcher` option is supported by Node's fetch at runtime but
-  // missing from the ambient RequestInit type, hence the cast.
-  return fetch(url, {
-    ...init,
-    dispatcher: proxyDispatcher,
-  } as RequestInit)
+export async function fetchWithProxy(url: string | URL, init?: RequestInit) {
+  try {
+    // The `dispatcher` option is supported by Node's fetch at runtime but
+    // missing from the ambient RequestInit type, hence the cast.
+    return await fetch(url, {
+      ...init,
+      dispatcher: proxyDispatcher,
+    } as RequestInit)
+  } catch (error) {
+    // Native fetch reports network failures as a generic "fetch failed"
+    // TypeError with the actual reason buried in `cause`.
+    if (error instanceof TypeError && error.cause) {
+      throw new Error(
+        `Request to ${url} failed, reason: ${getFailureReason(error.cause)}`,
+        { cause: error.cause }
+      )
+    }
+    throw error
+  }
+}
+
+function getFailureReason(cause: unknown): string {
+  // Connection failures surface as an AggregateError with an empty message
+  // and the per-address errors (e.g. ECONNREFUSED) in `errors`.
+  if (cause instanceof Error && "errors" in cause) {
+    const errors = (cause as Error & { errors: unknown }).errors
+    if (Array.isArray(errors) && errors.length) {
+      return getFailureReason(errors[0])
+    }
+  }
+
+  if (cause instanceof Error) {
+    return (
+      cause.message ||
+      (cause as NodeJS.ErrnoException).code ||
+      "unknown error"
+    )
+  }
+
+  return String(cause)
 }