fix(extgen): better error handling (#2370) #4679

Job	Run time
prepare	12s
Build macOS arm64 binaries	33m 20s
Build linux/arm64 static GNU binary	22m 16s
Build macOS x86_64 binaries	1h 33m 33s
Build linux/amd64 static musl binary (debug)	25m 58s
Build linux/amd64 static GNU binary	26m 50s
Build linux/arm64 static musl binary	25m 10s
Build linux/amd64 static musl binary (mimalloc)	2m 51s
Build linux/amd64 static musl binary	33m 34s
push	0s
	4h 23m 44s

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