Throw an error in checktask when a task failed

[efaulhaber]

Solves JuliaSIMD/Polyester.jl#153.

julia> @batch for j in axes(x, 2)
                  for i in 1:5
                      if i > 3 && j in (2, 4, 9)
                          error("some error")
                      end
                      x[i, j] = 1
                  end
              end
ERROR: TaskFailedException
Stacktrace:
 [1] checktask(tid::UInt32)
   @ ThreadingUtilities ~/.julia/dev/ThreadingUtilities/src/threadtasks.jl:74
 [2] wait
   @ ~/.julia/packages/ThreadingUtilities/3z3g0/src/threadtasks.jl:88 [inlined]
 [3] wait
   @ ~/.julia/packages/ThreadingUtilities/3z3g0/src/threadtasks.jl:81 [inlined]
 [4] macro expansion
   @ ~/.julia/packages/Polyester/eqrC9/src/batch.jl:257 [inlined]
 [5] _batch_no_reserve
   @ ~/.julia/packages/Polyester/eqrC9/src/batch.jl:168 [inlined]
 [6] batch(::var"#56#57", ::Val{…}, ::Tuple{}, ::Tuple{}, ::Tuple{…}, ::Static.StaticInt{…}, ::Static.StaticInt{…}, ::Polyester.NoLoop, ::Polyester.CombineIndices, ::Matrix{…})
   @ Polyester ~/.julia/packages/Polyester/eqrC9/src/batch.jl:334
 [7] top-level scope
   @ ~/.julia/packages/Polyester/eqrC9/src/closure.jl:456

    nested task error: some error
    Stacktrace:
     [1] error(s::String)
       @ Base ./error.jl:35
     [2] macro expansion
       @ ./REPL[25]:4 [inlined]
     [3] #56
       @ ~/.julia/packages/Polyester/eqrC9/src/closure.jl:309 [inlined]
     [4] (::Polyester.BatchClosure{var"#56#57", ManualMemory.Reference{Tuple{…}}, false, Tuple{}})(p::Ptr{UInt64})
       @ Polyester ~/.julia/packages/Polyester/eqrC9/src/batch.jl:11
     [5] _call
       @ ~/.julia/packages/ThreadingUtilities/3z3g0/src/threadtasks.jl:11 [inlined]
     [6] (::ThreadingUtilities.ThreadTask)()
       @ ThreadingUtilities ~/.julia/dev/ThreadingUtilities/src/threadtasks.jl:29
Some type information was truncated. Use `show(err)` to see complete types.

Note that JuliaSIMD/Polyester.jl#154 should probably get merged first.