Fix unmarshaler with comment #604

Job	Run time
Fuzzing Test	1m 14s
lint	12s
page	42s
Test in i386 (ubuntu-latest, 1.22)	8s
Test in i386 (ubuntu-latest, 1.23)	18s
Test with -race (ubuntu-latest, 1.23)	26s
Test in i386 (ubuntu-latest, 1.21)	15s
Test in i386 (windows-latest, 1.22)	1m 14s
Test in i386 (windows-latest, 1.21)	1m 40s
Test with -race (macos-latest, 1.21)	17s
Test in i386 (windows-latest, 1.23)	1m 33s
Test with -race (windows-latest, 1.21)	1m 47s
Test with -race (macos-latest, 1.22)	16s
Test with -race (ubuntu-latest, 1.21)	28s
Test with -race (ubuntu-latest, 1.22)	28s
Test with -race (windows-latest, 1.22)	2m 16s
Coverage	19s
ycat	5s
Test with -race (macos-latest, 1.23)	16s
Test with -race (windows-latest, 1.23)	2m 1s
	15m 55s

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