fix: add error message for file not found

bin/asar.js

@@ -61,8 +61,12 @@ program.command('extract-file <archive> <filename>')
   .alias('ef')
   .description('extract one file from archive')
   .action(function (archive, filename) {
-    require('fs').writeFileSync(require('path').basename(filename),
-      asar.extractFile(archive, filename))
+    try {
+      const fileData = asar.extractFile(archive, filename)
+      require('fs').writeFileSync(require('path').basename(filename), fileData)
+    } catch (err) {
+      console.log(err.message)
+    }
   })
 
 program.command('extract <archive> <dest>')

lib/asar.js

@@ -167,7 +167,12 @@ module.exports.listPackage = function (archive, options) {
 
 module.exports.extractFile = function (archive, filename) {
   const filesystem = disk.readFilesystemSync(archive)
-  return disk.readFileSync(filesystem, filename, filesystem.getFile(filename))
+  const file = filesystem.getFile(filename)
+  if (typeof file === 'undefined') {
+    return undefined
+  }
+
+  return disk.readFileSync(filesystem, filename, file)
 }
 
 module.exports.extractAll = function (archive, dest) {

lib/filesystem.js

@@ -139,6 +139,10 @@ class Filesystem {
     followLinks = typeof followLinks === 'undefined' ? true : followLinks
     const info = this.getNode(p)
 
+    if (typeof info === 'undefined') {
+      throw new Error(`The file "${p}" was not found in the archive.`)
+    }
+
     // if followLinks is false we don't resolve symlinks
     if (info.link && followLinks) {
       return this.getFile(info.link)

test/cli-spec.js

@@ -75,6 +75,9 @@ describe('command line interface', function () {
       assert.strictEqual(actual, expected)
     })
   */
+  it('should throw an error when trying to extract a non-existent file', async () => {
+    return assertAsarOutputMatches('ef test/input/extractthis.asar dir1/non-existent', 'test/expected/extractthis-non-existent-file.txt')
+  })
   it('should extract an archive', async () => {
     await execAsar('e test/input/extractthis.asar tmp/extractthis-cli/')
     return compDirs('tmp/extractthis-cli/', 'test/expected/extractthis')

test/expected/extractthis-non-existent-file.txt

@@ -0,0 +1 @@
+The file "dir1/non-existent" was not found in the archive.