fix: filter functions and undefined out of makeEnv

index.js

@@ -458,12 +458,17 @@ function makeEnv (data, opts, prefix, env) {
       return
     }
     var value = opts.config[i]
-    if (value instanceof Stream || Array.isArray(value)) return
+    if (value instanceof Stream || Array.isArray(value) || typeof value === 'function') return
     if (i.match(/umask/)) value = umask.toString(value)
+
     if (!value) value = ''
     else if (typeof value === 'number') value = '' + value
     else if (typeof value !== 'string') value = JSON.stringify(value)
 
+    if (typeof value !== 'string') {
+      return
+    }
+
     value = value.indexOf('\n') !== -1
       ? JSON.stringify(value)
       : value

test/index.js

@@ -20,7 +20,10 @@ test('makeEnv', function (t) {
     'myPackage:bar': 2,
     'myPackage:foo': 3,
     'myPackage@1.0.0:baz': 4,
-    'myPackage@1.0.0:foo': 5
+    'myPackage@1.0.0:foo': 5,
+    ignoreThisFunction: () => {},
+    jsonsAsUndefined: { toJSON: () => undefined },
+    jsonsAsFunction: { toJSON: () => () => {} }
   }
 
   const env = lifecycle.makeEnv(pkg, {
@@ -44,6 +47,10 @@ test('makeEnv', function (t) {
   t.equal('4', env.npm_package_config_baz, 'package@version config is included')
   t.equal('5', env.npm_package_config_foo, 'package@version config overrides package config')
 
+  t.equal(env.npm_package_config_ignoreThisFunction, undefined)
+  t.equal(env.npm_package_config_jsonsAsUndefined, undefined)
+  t.equal(env.npm_package_config_jsonsAsFunction, undefined)
+
   t.equal('--inspect-brk --abort-on-uncaught-exception', env.NODE_OPTIONS, 'nodeOptions sets NODE_OPTIONS')
   t.end()
 })