Added return to etl::optional emplace, fixed typo #499

Job	Run time
Syntax Check - Clang C++03 Linux No STL (ubuntu-22.04)	24s
Syntax Check - Clang C++03 Linux STL (ubuntu-22.04)	24s
Syntax Check - Clang C++11 Linux No STL (ubuntu-22.04)	39s
Syntax Check - Clang C++11 Linux No STL Force C++03 (ubuntu-22.04)	38s
Syntax Check - Clang C++11 Linux STL (ubuntu-22.04)	37s
Syntax Check - Clang C++11 Linux STL Force C++03 (ubuntu-22.04)	40s
Syntax Check - Clang C++14 Linux No STL (ubuntu-22.04)	39s
Syntax Check - Clang C++14 Linux No STL Force C++03 (ubuntu-22.04)	35s
Syntax Check - Clang C++14 Linux STL (ubuntu-22.04)	41s
Syntax Check - Clang C++14 Linux STL Force C++03 (ubuntu-22.04)	53s
Syntax Check - Clang C++17 Linux No STL (ubuntu-22.04)	42s
Syntax Check - Clang C++17 Linux No STL Force C++03 (ubuntu-22.04)	43s
Syntax Check - Clang C++17 Linux STL Force C++03 (ubuntu-22.04)	54s
Syntax Check - Clang C++17 Linux STL (ubuntu-22.04)	51s
Syntax Check - Clang C++20 Linux No STL (ubuntu-22.04)	1m 1s
Syntax Check - Clang C++20 Linux No STL Force C++03 (ubuntu-22.04)	1m 0s
Syntax Check - Clang C++20 Linux STL (ubuntu-22.04)	1m 20s
Syntax Check - Clang C++20 Linux STL Force C++03 (ubuntu-22.04)	1m 21s
	14m 2s

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