Handle elixir exceptions in MetadataReporter

[tmaszk]

I've been testing with the master branch and have discovered a class of errors that is causing MetadataReporter to throw an exception. It occurs when the original exception occurs within an async Task. This PR contains the fix and a unit test to exercise it.

[XiXiaPdx]

@tmaszk I have a question about the new test. I added the test to master, expecting it to fail the assertion but it passes instead. Here is what I see in events. Is that unexpected?

[test/error_test.exs:200: ErrorTest."test Catch a function clause error inside a Task"/1]
events #=> [
  [
    %{
      timestamp: 1707246881.171,
      type: "TransactionError",
      duration: nil,
      databaseDuration: nil,
      "error.class": "FunctionClauseError",
      "error.message": "(FunctionClauseError) no function clause matching in ErrorTest.ErrorDummy.handle_call/3",
      "error.expected": false,
      transactionName: "OtherTransaction/Elixir/ElixirProcess//ErrorTest.ErrorDummy"
    },
    %{
      process: "ErrorTest.ErrorDummy",
      stacktrace: "test/error_test.exs:11: ErrorTest.ErrorDummy.handle_call(:foo, nil, nil)\n(elixir 1.14.4) lib/task/supervised.ex:89: Task.Supervised.invoke_mfa/2\n(elixir 1.14.4) lib/task/supervised.ex:34: Task.Supervised.reply/4\n(stdlib 5.1.1) proc_lib.erl:241: :proc_lib.init_p_do_apply/3\nanonymous fn() in ErrorTest.\"test Catch a function clause error inside a Task\"/1",
      test_attribute: "test_value"
    },
    %{}
  ]
]

[tmaszk]

@XiXiaPdx Good question. In my local development, I added the code in this PR on top of #426

If you add the test to the code in #426, the test will fail.

I was trying to keep the PRs as atomic as I could, but I can combine this with #426 if you would rather.

[XiXiaPdx]

Oh, I see. Nice catch and thanks again for another contribution!

[XiXiaPdx]

After #426 is merged, let's merge this.