Fix onError hook

[ehmicky]

onError hooks receive the error instance as argument:

module.exports = {
  name: 'netlify-plugin-example',
  onError({ error }) {
    console.error(error)
  }
}

However plugins are spawned as child processes. The parent process communicates to them through child_process ipc which uses JSON as the message format. This leads to error instances being converted to plain objects, which makes them lose their Error prototype, message, name and stack properties.

This PR fixes this by serializing and parsing error instances ourselves.

Note that Node.js added support for v8 serialization (based on the HTML structured clone algorithm) yesterday! :D This is available in Node 13.2.0. Unfortunately the Node.js version of the parent process is the same as child processes, so we need to support Node down to 8.3.0 (see ongoing discussion #81).

Tagging @sdras since this is part of the ongoing "error handling" thread.

[codecov]

Codecov Report

Merging #512 into master will decrease coverage by 0.17%.
The diff coverage is 57.14%.

@@            Coverage Diff             @@
##           master     #512      +/-   ##
==========================================
- Coverage   90.74%   90.56%   -0.18%     
==========================================
  Files          47       47              
  Lines        1080     1092      +12     
  Branches      123      127       +4     
==========================================
+ Hits          980      989       +9     
- Misses         74       77       +3     
  Partials       26       26

Flag	Coverage Δ
#macOS	90.1% <57.14%> (-0.45%)	⬇️
#node_13	90.56% <57.14%> (-0.18%)	⬇️
#node_8_3_0	90.1% <57.14%> (-0.45%)	⬇️
#ubuntu	90.1% <57.14%> (-0.45%)	⬇️
#windows	86.06% <57.14%> (?)

Impacted Files	Coverage Δ
packages/build/src/plugins/ipc.js	83.33% <57.14%> (-11.12%)	⬇️
packages/build/src/log/main.js	96.93% <0%> (+1.02%)	⬆️
packages/build/src/telemetry/plugins.js	63.33% <0%> (+6.66%)	⬆️

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