[#184] *: Unify done contexts handling

If `ctx.Done()`, return `ctx.Err()` in every function that returns an error.

Signed-off-by: Pavel Karpy <p.karpy@yadro.com>

pkg/morph/client/client.go

@@ -340,7 +340,7 @@ func (c *Client) Wait(ctx context.Context, n uint32) error {
 	for {
 		select {
 		case <-ctx.Done():
-			return nil
+			return ctx.Err()
 		default:
 		}