[Fix] extensions: for invalid code where name does not exist, do …

…not crash

Fixes #1613

CHANGELOG.md

@@ -7,6 +7,7 @@ This change log adheres to standards from [Keep a CHANGELOG](http://keepachangel
 ## [Unreleased]
 ### Fixed
 - [`import/external-module-folders` setting] now correctly works with directories containing modules symlinked from `node_modules` ([#1605], thanks [@skozin])
+- [`extensions`]: for invalid code where `name` does not exist, do not crash ([#1613], thanks [@ljharb])
 
 ### Changed
 - [`import/external-module-folders` setting] behavior is more strict now: it will only match complete path segments ([#1605], thanks [@skozin])
@@ -641,6 +642,7 @@ for info on changes for earlier releases.
 
 [`memo-parser`]: ./memo-parser/README.md
 
+[#1613]: https://github.com/benmosher/eslint-plugin-import/issues/1613
 [#1605]: https://github.com/benmosher/eslint-plugin-import/pull/1605
 [#1589]: https://github.com/benmosher/eslint-plugin-import/issues/1589
 [#1586]: https://github.com/benmosher/eslint-plugin-import/pull/1586

src/core/importType.js

@@ -17,7 +17,7 @@ export function isAbsolute(name) {
 
 // path is defined only when a resolver resolves to a non-standard path
 export function isBuiltIn(name, settings, path) {
-  if (path) return false
+  if (path || !name) return false
   const base = baseModule(name)
   const extras = (settings && settings['import/core-modules']) || []
   return coreModules[base] || extras.indexOf(base) > -1
@@ -52,12 +52,12 @@ export function isExternalModuleMain(name, settings, path) {
 
 const scopedRegExp = /^@[^/]+\/?[^/]+/
 export function isScoped(name) {
-  return scopedRegExp.test(name)
+  return name && scopedRegExp.test(name)
 }
 
 const scopedMainRegExp = /^@[^/]+\/?[^/]+$/
 export function isScopedMain(name) {
-  return scopedMainRegExp.test(name)
+  return name && scopedMainRegExp.test(name)
 }
 
 function isInternalModule(name, settings, path) {