fix(instance_server): check empty bootscript (#2630)

Author: Codelax

internal/services/instance/server.go

@@ -612,7 +612,9 @@ func ResourceInstanceServerRead(ctx context.Context, d *schema.ResourceData, m i
 		_ = d.Set("zone", string(zone))
 		_ = d.Set("name", server.Name)
 		_ = d.Set("boot_type", server.BootType)
-		_ = d.Set("bootscript_id", server.Bootscript.ID)
+		if server.Bootscript != nil {
+			_ = d.Set("bootscript_id", server.Bootscript.ID)
+		}
 		_ = d.Set("type", server.CommercialType)
 		if len(server.Tags) > 0 {
 			_ = d.Set("tags", server.Tags)