fix: use pretty-error

Author: EndBug

lib/index.js

@@ -28,6 +28,7 @@
     "@actions/core": "^1.2.6",
     "axios": "^0.20.0",
     "github-label-sync": "github:EndBug/github-label-sync#typings-usable",
+    "pretty-error": "^2.1.1",
     "yamljs": "^0.3.0"
   },
   "devDependencies": {

package-lock.json

@@ -1,3 +1,5 @@
+require('pretty-error').start()
+
 import core, { getInput, setFailed } from '@actions/core'
 import githubLabelSync, { LabelInfo } from 'github-label-sync'
 import fs from 'fs'