Querying NULL image field causes driver to hang

[hqin]

Description

Querying NULL image field causes driver to hang

Expected behaviour

Querying NULL image field should return []byte(nil)

Querying NULL image field causes driver to hang

A clear and concise description of what currently happens.

Steps to Reproduce

Steps to reproduce the behavior:

1. Create a test table with a row with a NULL image field

create table DATATYPE_IMAGE_NULL_TEST(Id int primary key, ImageFld image NULL)
go

insert into DATATYPE_IMAGE_NULL_TEST values(1, NULL)
go

2. export environment variables "DB_USERNAME", "DB_PASSWORD", "DB_DATABASE", "DB_HOSTNAME", "DB_PORT",
3. Run the attached code image_null_validate.go using tds driver returns correct value

DB_DRIVER=tds go run image_null_validate.go
Connected to database using tds driver
select ImageFld from DATATYPE_IMAGE_NULL_TEST where Id=1
column[0]
	column name: ImageFld
	type: image
	length = 2147483647
	nullable = true
scan type: []uint8
ImageFld: []byte(nil)

4. Run the attached code image_null_validate.go using go-ase driver hangs

DB_DRIVER=ase go run image_null_validate.go
Connected to database using ase driver
select ImageFld from DATATYPE_IMAGE_NULL_TEST where Id=1
column[0]
	column name: ImageFld
	type: IMAGE
	length = 32768
	nullable = true
scan type: []uint8

Environment

Client:
OS: MacOS or Centos-7
go version: 1.16
go-ase version / commit hash: v0.0.0-20210611100756-1778dda08c18
go-dblib version / commit hash: v0.0.0-20210610133137-f25b0f0fced0
tds driver version: github.com/thda/tds v0.1.7

Server:
OS: Centos-7
ASE version: 16.0_SP03PL09_EBF29247

Screenshots

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Additional context

Add any other context about the problem here.
image_null_validate.go.gz