Do not print error banner for shell proxy commands

There are a few commands (exec, run-script, and the run-script proxies)
where essentially npm is acting like a very fancy shell.  It is peculiar
and noisy for npm to print a verbose error banner at the end of these
commands, since presumably the command itself already did whatever it
had to do to report the error appropriately.

For example, `npm test` runs a test script, usually outputting test
results.  Having npm then tell me that my tests failed with exit status
1 and print a debug log, is unnecessary and unwanted.

When the error encountered for these commands does not have a non-zero
numeric 'code', then we still print the standard npm error reporting
messages, because presumably something went wrong OTHER than a process
exiting with a non-zero status code.

PR-URL: https://github.com/npm/cli/pull/2742
Credit: @isaacs
Close: #2742
Reviewed-by: @nlf

3 files changed, 30 insertions, 3 deletions

diff --git a/lib/npm.js b/lib/npm.js
index 40aa9bbd9..85dc67a78 100644
--- a/lib/npm.js
+++ b/lib/npm.js
@@ -49,6 +49,7 @@ const makeCmd = cmd => {
 }
 
 const { types, defaults, shorthands } = require('./utils/config.js')
+const { shellouts } = require('./utils/cmd-list.js')
 
 let warnedNonDashArg = false
 const _runCmd = Symbol('_runCmd')
@@ -81,6 +82,10 @@ const npm = module.exports = new class extends EventEmitter {
     this.updateNotification = null
   }
 
+  get shelloutCommands () {
+    return shellouts
+  }
+
   deref (c) {
     return deref(c)
   }
diff --git a/lib/utils/cmd-list.js b/lib/utils/cmd-list.js
index 4e088c12d..336e4dd54 100644
--- a/lib/utils/cmd-list.js
+++ b/lib/utils/cmd-list.js
@@ -136,10 +136,24 @@ const cmdList = [
 ]
 
 const plumbing = ['birthday', 'help-search']
+
+// these commands just shell out to something else or handle the
+// error themselves, so it's confusing and weird to write out
+// our full error log banner when they exit non-zero
+const shellouts = [
+  'exec',
+  'run-script',
+  'test',
+  'start',
+  'stop',
+  'restart',
+]
+
 module.exports = {
   aliases: Object.assign({}, shorthands, affordances),
   shorthands,
   affordances,
   cmdList,
   plumbing,
+  shellouts,
 }
diff --git a/lib/utils/error-handler.js b/lib/utils/error-handler.js
index f9685c91d..1fc31df44 100644
--- a/lib/utils/error-handler.js
+++ b/lib/utils/error-handler.js
@@ -105,8 +105,7 @@ const exit = (code, noLog) => {
 
   if (code && !noLog)
     writeLogFile()
-  else
-    reallyExit()
+  reallyExit()
 }
 
 const errorHandler = (er) => {
@@ -130,7 +129,16 @@ const errorHandler = (er) => {
   cbCalled = true
   if (!er)
     return exit(0)
-  if (typeof er === 'string') {
+
+  // if we got a command that just shells out to something else, then it
+  // will presumably print its own errors and exit with a proper status
+  // code if there's a problem.  If we got an error with a code=0, then...
+  // something else went wrong along the way, so maybe an npm problem?
+  const isShellout = npm.shelloutCommands.includes(npm.command)
+  const quietShellout = isShellout && typeof er.code === 'number' && er.code
+  if (quietShellout)
+    return exit(er.code, true)
+  else if (typeof er === 'string') {
     log.error('', er)
     return exit(1, true)
   } else if (!(er instanceof Error)) {