fix(agent): wrap transport errors in FireflyError

agent/tests/test_firefly.py

@@ -47,3 +47,11 @@ def test_accounts_walks_all_pages():
 
     accounts = make_client(handler).accounts()
     assert [a["attributes"]["name"] for a in accounts] == ["NFCU Checking", "Venmo"]
+
+
+def test_transport_errors_wrapped_in_firefly_error():
+    def handler(request: httpx.Request) -> httpx.Response:
+        raise httpx.ConnectError("connection refused")
+
+    with pytest.raises(FireflyError, match="ConnectError"):
+        make_client(handler).about()