check nil pointer on close clients

Author: asmyasnikov

internal/ratelimiter/client.go

@@ -32,6 +32,9 @@ type Client struct {
 }
 
 func (c *Client) Close(ctx context.Context) error {
+	if c == nil {
+		return xerrors.WithStackTrace(errNilClient)
+	}
 	return nil
 }
 

internal/scheme/client.go

@@ -29,6 +29,9 @@ type Client struct {
 }
 
 func (c *Client) Close(_ context.Context) error {
+	if c == nil {
+		return xerrors.WithStackTrace(errNilClient)
+	}
 	return nil
 }
 

internal/scripting/client.go

@@ -246,6 +246,9 @@ func (c *Client) streamExecute(
 }
 
 func (c *Client) Close(ctx context.Context) (err error) {
+	if c == nil {
+		return xerrors.WithStackTrace(errNilClient)
+	}
 	onDone := trace.ScriptingOnClose(c.config.Trace(), &ctx)
 	defer func() {
 		onDone(err)

internal/table/client.go

@@ -464,6 +464,10 @@ func (c *Client) Put(ctx context.Context, s Session) (err error) {
 // It returns first error occurred during stale sessions' deletion.
 // Note that even on error it calls Close() on each session.
 func (c *Client) Close(ctx context.Context) (err error) {
+	if c == nil {
+		return xerrors.WithStackTrace(errNilClient)
+	}
+
 	onDone := trace.TableOnClose(c.config.Trace(), &ctx)
 	defer func() {
 		onDone(err)