Do not print warnings about unhandled rejection

Author: ehmicky

src/handle/common.js

@@ -1,5 +1,6 @@
 import { isLimited } from '../limit.js'
 import { isRepeated } from '../repeat.js'
+import { isRejectionWarning } from '../warnings.js'
 import { getLevel } from '../level.js'
 import { getError, addErrorPrint } from '../error/main.js'
 import { exitProcess } from '../exit.js'
@@ -33,6 +34,10 @@ export const handleEvent = async function({
     return
   }
 
+  if (isRejectionWarning(name, event)) {
+    return
+  }
+
   await logEvent({ opts, name, event })
 
   await exitProcess({ name, opts })

src/warnings.js

@@ -46,3 +46,14 @@ const getWarningListeners = function() {
 }
 
 const warningListener = getWarningListener()
+
+// Unhandled rejected promises emit a warning by default (unless
+// --unhandled-rejections is used). This warning is not useful, so we remove it.
+export const isRejectionWarning = function(name, { value }) {
+  return (
+    name === 'warning' &&
+    value instanceof Error &&
+    value.name === 'DeprecationWarning' &&
+    value.code === 'DEP0018'
+  )
+}