[#287] client: Fix error handling after dialing

Before, when error was presented and neither `Canceled` nor
`DeadlineExceeded`, that method returned no error on failed dial.

Signed-off-by: Aleksey Savchuk <a.savchuk@yadro.com>

client/client.go

@@ -106,26 +106,28 @@ func (c *Client) Dial(ctx context.Context, prm PrmDial) error {
 	_, err := rpc.Balance(&c.c, new(v2accounting.BalanceRequest),
 		client.WithContext(ctx),
 	)
-	if err != nil {
-		var ctxErr error
 
-		// return context errors since they signal about dial problem
-		if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
-			ctxErr = err
-		} else if st, ok := status.FromError(err); ok && st.Code() == codes.Canceled {
-			ctxErr = context.Canceled
-		} else if ok && st.Code() == codes.DeadlineExceeded {
-			ctxErr = context.DeadlineExceeded
-		}
-		if ctxErr != nil {
-			if conn := c.c.Conn(); conn != nil {
-				_ = conn.Close()
-			}
-			return ctxErr
-		}
+	if err == nil {
+		return nil
 	}
 
-	return nil
+	var ctxErr error
+
+	switch st, ok := status.FromError(err); {
+	case errors.Is(err, context.Canceled) || (ok && st.Code() == codes.Canceled):
+		ctxErr = context.Canceled
+	case errors.Is(err, context.DeadlineExceeded) || (ok && st.Code() == codes.DeadlineExceeded):
+		ctxErr = context.DeadlineExceeded
+	default:
+	}
+
+	if ctxErr == nil {
+		return err
+	}
+	if conn := c.c.Conn(); conn != nil {
+		_ = conn.Close()
+	}
+	return ctxErr
 }
 
 // sets underlying provider of frostFSAPIServer. The method is used for testing as an approach