Add a map_err in speaker notes (#2155) #5863

Job	Run time
cargo (ubuntu-latest)	32s
bare-metal (src/bare-metal/alloc-example, aarch64-unknown-none)	32s
bare-metal (src/bare-metal/aps/examples, aarch64-unknown-none)	27s
cargo (macos-latest)	24s
find-languages	4s
bare-metal (src/bare-metal/microcontrollers/examples, thumbv7em-none-eabihf)	42s
format	35s
bare-metal (src/exercises/bare-metal/compass, thumbv7em-none-eabihf)	46s
typos	5s
bare-metal (src/exercises/bare-metal/rtc, aarch64-unknown-none)	27s
build (bn)	3m 31s
build (da)	3m 51s
build (de)	3m 22s
build (el)	3m 14s
build (en)	3m 42s
build (es)	3m 13s
build (fa)	3m 15s
build (fr)	3m 24s
build (id)	3m 7s
build (it)	3m 19s
build (ja)	4m 58s
build (ko)	4m 22s
build (pl)	3m 11s
build (pt-BR)	3m 25s
build (ro)	4m 0s
build (ru)	3m 15s
build (tr)	3m 55s
build (uk)	3m 41s
build (vi)	3m 23s
build (zh-CN)	4m 38s
build (zh-TW)	4m 17s
	1h 21m 37s

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