Improve error handling #414

Job	Run time
clang++-10/canary/c++17/Debug	3m 57s
tabtokens/clang++-10/canary/c++17/Debug	2m 21s
clang++-10/canary/c++17/Release	5m 15s
tabtokens/clang++-10/canary/c++17/Release	3m 6s
clang++-10/canary/c++20/Debug	4m 16s
tabtokens/clang++-10/canary/c++20/Debug	2m 34s
clang++-10/canary/c++20/Release	6m 11s
tabtokens/clang++-10/canary/c++20/Release	3m 19s
clang++-6.0/canary/c++11/Debug	3m 22s
tabtokens/clang++-6.0/canary/c++11/Debug	2m 4s
clang++-6.0/canary/c++11/Release	4m 29s
tabtokens/clang++-6.0/canary/c++11/Release	3m 11s
clang++-10/extended/c++11/Debug	6m 5s
clang++-10/extended/c++11/Release	8m 41s
clang++-10/san/c++11/Debug	4m 9s
clang++-10/san/c++11/Debug	3m 47s
clang++-10/san/c++11/Debug	4m 29s
clang++-10/san/c++11/Debug	4m 22s
clang++-10/san/c++11/Release	3m 54s
clang++-10/san/c++11/Release	4m 2s
clang++-10/san/c++11/Release	4m 14s
clang++-10/san/c++11/Release	4m 8s
clang++-10/san/c++17/Debug	4m 15s
clang++-10/san/c++17/Debug	4m 12s
clang++-10/san/c++17/Debug	4m 36s
clang++-10/san/c++17/Debug	4m 28s
clang++-10/san/c++17/Release	3m 54s
clang++-10/san/c++17/Release	3m 56s
clang++-10/san/c++17/Release	4m 15s
clang++-10/san/c++17/Release	4m 24s
clang++-10/san/c++20/Debug	4m 29s
clang++-10/san/c++20/Debug	4m 13s
clang++-10/san/c++20/Debug	5m 5s
clang++-10/san/c++20/Debug	4m 47s
clang++-10/san/c++20/Release	4m 1s
clang++-10/san/c++20/Release	4m 6s
clang++-10/san/c++20/Release	4m 25s
clang++-10/san/c++20/Release	4m 26s
	2h 41m 28s

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