Diagnostics report: inspect the error object

[mmarchini]

Is your feature request related to a problem? Please describe.
Now we inspect the error object on fatal errors, which is awesome. I started to play with node-report recently and this feature was not incorporated there yet. I think this would make a lot of sense since it would make the report more useful for users.

Describe the solution you'd like
Take the program below as an example:

// crash.js
function crash() { 
  let e = new Error('boom'); 
  e.val = 1; 
  throw e;
} 

crash();

Today it will output the following stack trace (see how it also prints the custom attribute we added):

$ ./node ./crash.js
/home/mmarchini/workspace/nodejs/node/crash.js:5
  throw e;
  ^

Error: boom
    at crash (/home/mmarchini/workspace/nodejs/node/crash.js:3:11)
    at Object.<anonymous> (/home/mmarchini/workspace/nodejs/node/crash.js:8:1)
    at Module._compile (internal/modules/cjs/loader.js:779:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:790:10)
    at Module.load (internal/modules/cjs/loader.js:642:32)
    at Function.Module._load (internal/modules/cjs/loader.js:555:12)
    at Function.Module.runMain (internal/modules/cjs/loader.js:842:10)
    at internal/main/run_main_module.js:17:11 {
  val: 1
}

The report for this error looks like this today:

  "javascriptStack": {
    "message": "[eval]:1",
    "stack": [
      "at crash (/home/mmarchini/workspace/nodejs/node/crash.js:3:11)",
      "at Object.<anonymous> (/home/mmarchini/workspace/nodejs/node/crash.js:8:1)",
      "at Module._compile (internal/modules/cjs/loader.js:779:30)",
      "at Object.Module._extensions..js (internal/modules/cjs/loader.js:790:10)",
      "at Module.load (internal/modules/cjs/loader.js:642:32)",
      "at Function.Module._load (internal/modules/cjs/loader.js:555:12)",
      "at Function.Module.runMain (internal/modules/cjs/loader.js:842:10)"
    ]
  },

It would be amazing if we had the properties as well, as shown below:

  "javascriptStack": {
    "message": "[eval]:1",
    "stack": [
      "at crash (/home/mmarchini/workspace/nodejs/node/crash.js:3:11)",
      "at Object.<anonymous> (/home/mmarchini/workspace/nodejs/node/crash.js:8:1)",
      "at Module._compile (internal/modules/cjs/loader.js:779:30)",
      "at Object.Module._extensions..js (internal/modules/cjs/loader.js:790:10)",
      "at Module.load (internal/modules/cjs/loader.js:642:32)",
      "at Function.Module._load (internal/modules/cjs/loader.js:555:12)",
      "at Function.Module.runMain (internal/modules/cjs/loader.js:842:10)"
    ],
    "errorProperties": {
      "val": 1
    }
  },

Describe alternatives you've considered
The only alternative as powerful as this would be core dumps, but the entry barrier for core dumps is way higher than node-report.

[himself65]

related code lines:

node/src/node_report.cc

Lines 352 to 388 in c42da5e

	static void PrintJavaScriptStack(JSONWriter* writer,
	Isolate* isolate,
	Local<String> stackstr,
	const char* trigger) {
	writer->json_objectstart("javascriptStack");
	std::string ss;
	if ((!strcmp(trigger, "FatalError")) ||
	(!strcmp(trigger, "Signal"))) {
	ss = "No stack.\nUnavailable.\n";
	} else {
	String::Utf8Value sv(isolate, stackstr);
	ss = std::string(*sv, sv.length());
	}
	int line = ss.find('\n');
	if (line == -1) {
	writer->json_keyvalue("message", ss);
	writer->json_objectend();
	} else {
	std::string l = ss.substr(0, line);
	writer->json_keyvalue("message", l);
	writer->json_arraystart("stack");
	ss = ss.substr(line + 1);
	line = ss.find('\n');
	while (line != -1) {
	l = ss.substr(0, line);
	l.erase(l.begin(), std::find_if(l.begin(), l.end(), [](int ch) {
	return !std::iswspace(ch);
	}));
	writer->json_element(l);
	ss = ss.substr(line + 1);
	line = ss.find('\n');
	}
	}
	writer->json_arrayend();
	writer->json_objectend();
	}

[himself65]

I'm working on this.

[himself65]

I think I've done this, see #28426

[himself65]

landed in 870f0fc