Fix error message for wrong size description_hash.

lnrpc/invoicesrpc/addinvoice.go

@@ -159,8 +159,8 @@ func AddInvoice(ctx context.Context, cfg *AddInvoiceConfig,
 			"(maxsize=%v)", len(invoice.Receipt), channeldb.MaxReceiptSize)
 	}
 	if len(invoice.DescriptionHash) > 0 && len(invoice.DescriptionHash) != 32 {
-		return nil, nil, fmt.Errorf("description hash is %v bytes, must be %v",
-			len(invoice.DescriptionHash), channeldb.MaxPaymentRequestSize)
+		return nil, nil, fmt.Errorf("description hash is %v bytes, must be 32",
+			len(invoice.DescriptionHash))
 	}
 
 	// The value of the invoice must not be negative.