adjust metadata_reporter :transaction report_error

[rlchu]

This PR fixes a bug within lib/new_relic/error/metadata_reporter.ex which can emerge when upgrading from Elixir 1.14 to 1.15 which could manifest as reported errors which were formerly on the Elixir level could report as being wrapped on the Erlang level.

Compare to the use of the NewRelic.Transaction.Reporter.error in this PR to here:

elixir_agent/lib/new_relic/error/reporter.ex

Line 38 in 56525d9

reason: exception,

-- can see the reason should be an exception struct (which I believe is further parsed as part of the collection cycle), not the "reason" string explanation

NewRelic.Transaction.Reporter.error(%{
      kind: kind,
      reason: exception,
      stack: stacktrace
    })

this reason exception and stacktrace can be extracted directly from the metadata.reason tuple:
{_exception_type, reason, stacktrace, _expected} = parse_reason(metadata.reason)
can instead simply be {exception, stacktrace} = metadata.reason.

When a direct 'reason' string was being passed instead of the expected exception struct, this can manifest as an 'erlang wrapped' error in reporting -- what was (ErrorType) <message> becomes (ErlangError) Erlang Error: (ErrorType) <msesage> and further metadata is misreported, including for example expected errors being flipped to false (as a result of landing here

elixir_agent/lib/new_relic/error/metadata_reporter.ex

Line 73 in 56525d9

defp parse_reason({exception, stacktrace}) do

)

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[tpitale]

Thank you! Good catch, that's a tricky one.