[client] Fix race conditions (#2869)

* Fix concurrent map access in status

* Fix race when retrieving ctx state error

* Fix race when accessing service controller server instance

client/cmd/service.go

@@ -2,6 +2,7 @@ package cmd
 
 import (
 	"context"
+	"sync"
 
 	"github.com/kardianos/service"
 	log "github.com/sirupsen/logrus"
@@ -13,10 +14,11 @@ import (
 )
 
 type program struct {
-	ctx            context.Context
-	cancel         context.CancelFunc
-	serv           *grpc.Server
-	serverInstance *server.Server
+	ctx              context.Context
+	cancel           context.CancelFunc
+	serv             *grpc.Server
+	serverInstance   *server.Server
+	serverInstanceMu sync.Mutex
 }
 
 func newProgram(ctx context.Context, cancel context.CancelFunc) *program {