Errors in remote asynchronous tasks lose their error message when displayed on the caller on Julia 1.6

[jishnub]

Cross-posting from discourse as there was no response there

On Julia 1.6:

julia> @fetchfrom 2 @sync @async error("errmsg")
ERROR: On worker 2:
TaskFailedException

    nested task error: 
Stacktrace:
 [1] sync_end
   @ ./task.jl:364
 [2] macro expansion
   @ ./task.jl:383 [inlined]
 [3] #55
   @ /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Distributed/src/macros.jl:149
 [4] #106
   @ /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Distributed/src/process_messages.jl:278
 [5] run_work_thunk
   @ /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Distributed/src/process_messages.jl:63
 [6] macro expansion
   @ /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Distributed/src/process_messages.jl:278 [inlined]
 [7] #105
   @ ./task.jl:406
Stacktrace:
 [1] #remotecall_fetch#143
   @ /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Distributed/src/remotecall.jl:394 [inlined]
 [2] remotecall_fetch(::Function, ::Distributed.Worker)
   @ Distributed /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Distributed/src/remotecall.jl:386
 [3] remotecall_fetch(::Function, ::Int64; kwargs::Base.Iterators.Pairs{Union{}, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
   @ Distributed /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Distributed/src/remotecall.jl:421
 [4] remotecall_fetch(::Function, ::Int64)
   @ Distributed /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Distributed/src/remotecall.jl:421
 [5] top-level scope
   @ REPL[14]:1

The error message is lost here. If we do something similar on a local process,

julia> @sync @async error("errmsg")
ERROR: TaskFailedException

    nested task error: errmsg
    Stacktrace:
     [1] error(s::String)
       @ Base ./error.jl:33
     [2] (::var"#61#62")()
       @ Main ./task.jl:406
Stacktrace:
 [1] sync_end(c::Channel{Any})
   @ Base ./task.jl:364
 [2] top-level scope
   @ task.jl:383

the error message is displayed correctly. This also works correctly if the remote error is not wrapped in @async:

julia> @fetchfrom 2 error("errmsg")
ERROR: On worker 2:
errmsg
Stacktrace:
 [1] error
   @ ./error.jl:33
 [2] #63
   @ /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Distributed/src/macros.jl:149
 [3] #106
   @ /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Distributed/src/process_messages.jl:278
 [4] run_work_thunk
   @ /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Distributed/src/process_messages.jl:63
 [5] macro expansion
   @ /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Distributed/src/process_messages.jl:278 [inlined]
 [6] #105
   @ ./task.jl:406
Stacktrace:
 [1] #remotecall_fetch#143
   @ /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Distributed/src/remotecall.jl:394 [inlined]
 [2] remotecall_fetch(::Function, ::Distributed.Worker)
   @ Distributed /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Distributed/src/remotecall.jl:386
 [3] remotecall_fetch(::Function, ::Int64; kwargs::Base.Iterators.Pairs{Union{}, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
   @ Distributed /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Distributed/src/remotecall.jl:421
 [4] remotecall_fetch(::Function, ::Int64)
   @ Distributed /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Distributed/src/remotecall.jl:421
 [5] top-level scope
   @ REPL[17]:1

This worked correctly on 1.5.4:

julia> @fetchfrom 2 @sync @async error("errmsg")
ERROR: On worker 2:
TaskFailedException:
errmsg
error at ./error.jl:33
#2 at ./task.jl:356
Stacktrace:
 [1] #remotecall_fetch#143 at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:394 [inlined]
 [2] remotecall_fetch(::Function, ::Distributed.Worker) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:386
 [3] remotecall_fetch(::Function, ::Int64; kwargs::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:421
 [4] remotecall_fetch(::Function, ::Int64) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:421
 [5] top-level scope at REPL[1]:1

Edit: It appears that the error is propagated correctly on Julia 1.6, so this is a display issue?

julia> e = try
       @fetchfrom 2 @sync @async error("errmsg")
       catch e
       e
       end;

julia> t = e.captured.ex.exceptions[1];

julia> t.task.result
ErrorException("errmsg")