Fix incorrect this.channel access #1036

Job	Run time
cpp-lib-build (macos-11, clang, ON)	8m 6s
cpp-lib-build (macos-11, clang, OFF)	8m 45s
build (macos-11, tool)	1m 55s
cpp-lib-build (macos-11, gcc, ON)	7m 50s
build (macos-11, cpp)	34m 34s
cpp-lib-build (macos-11, gcc, OFF)	9m 22s
build (macos-11, csharp)	9m 26s
cpp-lib-build (ubuntu-20.04, clang, ON)	3m 17s
build (macos-11, dart)	6m 56s
cpp-lib-build (ubuntu-20.04, clang, OFF)	3m 25s
build (macos-11, go)	4m 43s
cpp-lib-build (ubuntu-20.04, gcc, ON)	3m 22s
build (macos-11, java)	8m 14s
cpp-lib-build (ubuntu-20.04, gcc, OFF)	3m 28s
build (macos-11, javascript)	2m 33s
cpp-lib-build (windows-2022, clang, ON)	4m 10s
build (macos-11, typescript)	19m 38s
cpp-lib-build (windows-2022, clang, OFF)	5m 55s
build (macos-11, php)	24s
cpp-lib-build (windows-2022, cl)	4m 45s
build (macos-11, python3)	2m 4s
build (ubuntu-20.04, tool)	58s
build (ubuntu-20.04, cpp)	17m 7s
build (ubuntu-20.04, csharp)	5m 11s
build (ubuntu-20.04, dart)	3m 16s
build (ubuntu-20.04, go)	2m 27s
build (ubuntu-20.04, java)	1m 20s
build (ubuntu-20.04, javascript)	1m 22s
build (ubuntu-20.04, typescript)	9m 59s
build (ubuntu-20.04, php)	1m 49s
build (ubuntu-20.04, python3)	1m 11s
build (windows-2022, tool)	1m 29s
build (windows-2022, cpp)	22m 57s
build (windows-2022, csharp)	6m 49s
build (windows-2022, dart)	4m 35s
build (windows-2022, go)	6m 15s
build (windows-2022, java)	1m 51s
build (windows-2022, javascript)	2m 26s
build (windows-2022, typescript)	20m 42s
build (windows-2022, php)	3m 21s
build (windows-2022, python3)	3m 13s
	4h 31m 10s

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