Does not support inspecting Errors in v8.x

[joyeecheung]

Looks like v8 has made some significant changes to errors (rewrite in C++), now they are no longer normal objects. The inspection seems to have stopped working since 7.x. I am working on a fix.

[mmarchini]

@joyeecheung is this still an issue?

[joyeecheung]

@mmarchini Yes.

With this:

diff --git a/test/fixtures/inspect-scenario.js b/test/fixtures/inspect-scenario.js
index 11133ac..03a508a 100644
--- a/test/fixtures/inspect-scenario.js
+++ b/test/fixtures/inspect-scenario.js
@@ -57,6 +57,10 @@ function closure() {
   );
   c.hashmap['buffer'] = Buffer.from([0xff, 0xf0, 0x80, 0x0f, 0x01, 0x00]);

+  c.hashmap['error'] = new Error('test');
+  c.hashmap['error'].code = 'ERR_TEST';
+  c.hashmap['error'].errno = 1;
+
   c.hashmap[0] = null;
   c.hashmap[4] = undefined;
   c.hashmap[23] = /regexp/;

I got:

.error=0x00000c0ad02d0b59:<unknown>,

[mmarchini]

@joyeecheung are you still working on this? If not, would you mind if I take this on?

[joyeecheung]

@mmarchini I probably lost the initial investigation with my last laptop...feel free to take this!

[mmarchini]

Adding a new postmortem metadata to V8 (JS_ERROR_TYPE) does the trick, but the .stack property is still unrecognized by llnode:

0x00003347c1720999:<Object: Error properties {
    .stack=<unknown field type>,
    .message=0x000033477c697aa9:<String: "test">,
    .<non-string>=0x00003347c1720bd1:<Array: length=46>,
    .code=0x000033477f7d1cc1:<String: "ERR_TEST">,
    .errno=<Smi: 1>}>

[misterdjules]

@mmarchini Isn't the stack property an accessor that replaces itself with a data property at runtime with the formatted stack trace? Could that explain why llnode has some difficulties displaying some useful info about it?

[mmarchini]

@misterdjules yep, that's what I got so far as well. The actual stack trace seems to be stored in the .<non-string>=0x00003347c1720bd1:<Array: length=46>, unfolding it should be enough to get a nice stack trace for the Error object. I'm also working on #156 to display the symbol of this property correctly.