Duel.HintSelection: Fix malformed message generation if nil was passed #859

Job	Run time
Linux-gcc-14	1m 11s
Android (21.4.7075529)	2m 58s
Mac-os-aarch64-cctools	2m 12s
Android (16.1.4479499)	5m 48s
Linux-musl (travis-core-linux-musl)	1m 27s
Android (26.1.10909125)	2m 17s
Mac-os-cctools	2m 6s
Linux-musl (travis-core-linux-musl-apicheck)	1m 28s
Linux-musl (travis-core-linux-musl-aarch64)	1m 32s
Windows-mingw (win32)	1m 42s
Windows-mingw (x64)	1m 57s
Windows-visual-studio (Win32)	1m 53s
Windows-visual-studio (x64)	2m 5s
Windows-visual-studio (ARM)	1m 53s
Windows-visual-studio (ARM64)	1m 50s
Mac-os-universal-cctools	9s
Notify-success	3s
	32m 31s

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