Return errors for Go Local Vault marshal failures

client_test.go

@@ -105,3 +105,33 @@ func TestBearerClientCanCallTenantEndpoints(t *testing.T) {
 		t.Fatalf("unexpected streams: %#v", streams)
 	}
 }
+
+func TestRelayLocalVaultEventReturnsMarshalError(t *testing.T) {
+	called := false
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		called = true
+		t.Fatalf("request should not be sent when local vault event body cannot be marshaled")
+	}))
+	defer server.Close()
+
+	client, err := NewClient(testAPIKey, WithBaseURL(server.URL), WithMaxRetries(1))
+	if err != nil {
+		t.Fatalf("client: %v", err)
+	}
+
+	_, err = client.RelayLocalVaultEvent(
+		context.Background(),
+		"lv_123",
+		M{"source": "local-vault"},
+		M{"bad": func() {}},
+		strings.Repeat("a", 64),
+		strings.Repeat("b", 128),
+		strings.Repeat("c", 64),
+	)
+	if err == nil || !strings.Contains(err.Error(), "marshal local vault event") {
+		t.Fatalf("expected marshal error, got %v", err)
+	}
+	if called {
+		t.Fatalf("request was sent after marshal failure")
+	}
+}