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Following this question and the comments made, together with the information in this question, the following code allows error tracking and debugging very nicely.

SetAttributes[withTaggedMsg, HoldAll];

withTaggedMsg[sym_] := Function[,
    MessagePacket[name__, BoxData[obj_, form_]] /; ! TrueQ[$tagMsg] :=
          Block[{$tagMsg = True},
        Identity@MessagePacket[name, BoxData[RowBox[{
          ToBoxes @ Style[
            Row[{"At iteration", HoldForm[sym], "=", sym, Spacer[5]}, " "],
        obj}], form]]
  ], HoldAll];

f[var : _] :=
    arg = var;

Map[f[#] &, Range[-2, 1, 1]] // withTaggedMsg[arg]

(*At iteration arg=0  Power::infy : Infinity expression 1/0 encountered.
{-(1/2), -1, ComplexInfinity, 1}*)

Now, the big problem is how to use withTaggedMsg together with ParallelMap instead of Map.

ParallelMap[f[#] &, Range[-2, 1, 1]] // withTaggedMsg[arg]

(*At iteration arg=arg Parallel`Protected`PacketHandler::default: Unhandled packet MessagePacket[Power,infy,BoxData[RowBox[{StyleBox[RowBox[{Power,::,infy}],
MessageName],: ,"Infinite expression \!\(1\/0\) encountered."}],StandardForm]] received and discarded from KernelObject[6,local].
{-(1/2), -1, ComplexInfinity, 1}*)

I don't see how I could do it, and would appreciate immensely if I could get some input in this.


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