fix(api): show clean RPC error messages

server/router/api/v1/connect_handler.go

@@ -4,6 +4,7 @@ import (
 	"net/http"
 
 	"connectrpc.com/connect"
+	"github.com/pkg/errors"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 
@@ -67,7 +68,7 @@ func convertGRPCError(err error) error {
 		return nil
 	}
 	if st, ok := status.FromError(err); ok {
-		return connect.NewError(grpcCodeToConnectCode(st.Code()), err)
+		return connect.NewError(grpcCodeToConnectCode(st.Code()), errors.New(st.Message()))
 	}
 	return connect.NewError(connect.CodeInternal, err)
 }

server/router/api/v1/connect_handler_test.go

@@ -0,0 +1,29 @@
+package v1
+
+import (
+	"strings"
+	"testing"
+
+	"connectrpc.com/connect"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+func TestConvertGRPCErrorUsesStatusMessage(t *testing.T) {
+	const message = "invalid username: must start with a lowercase letter"
+
+	err := convertGRPCError(status.Error(codes.InvalidArgument, message))
+	connectErr, ok := err.(*connect.Error)
+	if !ok {
+		t.Fatalf("convertGRPCError() returned %T, want *connect.Error", err)
+	}
+	if got := connectErr.Code(); got != connect.CodeInvalidArgument {
+		t.Fatalf("convertGRPCError() code = %v, want %v", got, connect.CodeInvalidArgument)
+	}
+	if got := connectErr.Message(); got != message {
+		t.Fatalf("convertGRPCError() message = %q, want %q", got, message)
+	}
+	if strings.Contains(connectErr.Message(), "rpc error:") {
+		t.Fatalf("convertGRPCError() message contains gRPC transport details: %q", connectErr.Message())
+	}
+}