From 5388bb116834196e1b0a9bd9f2622f36e842b3be Mon Sep 17 00:00:00 2001
From: Christopher Vogt <oss.nsp@cvogt.org>
Date: Sun, 19 Mar 2017 19:52:56 -0400
Subject: better error than NullPointerException when directory does not exist

---
 build/build.scala       | 2 +-
 stage1/Stage1.scala     | 4 ++--
 stage1/cbt.scala        | 1 +
 stage2/BasicBuild.scala | 4 ++--
 stage2/Lib.scala        | 2 +-
 5 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/build/build.scala b/build/build.scala
index 141b0a4..496acdc 100644
--- a/build/build.scala
+++ b/build/build.scala
@@ -17,5 +17,5 @@ class Build(val context: Context) extends Shared with PublishLocal{
 
   override def sources = Seq(
     "nailgun_launcher", "stage1", "stage2", "compatibility"
-  ).map( projectDirectory / _ ).flatMap( _.listFiles )
+  ).map( projectDirectory / _ ).flatMap( _.listOrFail )
 }
diff --git a/stage1/Stage1.scala b/stage1/Stage1.scala
index 62cab87..c243cc0 100644
--- a/stage1/Stage1.scala
+++ b/stage1/Stage1.scala
@@ -92,8 +92,8 @@ object Stage1{
 
     val stage2sourceFiles = (
       stage2.listFiles
-      ++ (stage2 / "plugins").listFiles
-      ++ (cbtHome / "libraries" / "eval").listFiles
+      ++ (stage2 / "plugins").listOrFail
+      ++ (cbtHome / "libraries" / "eval").listOrFail
     ).filter(_.isFile).filter(_.toString.endsWith(".scala"))
 
     val cls = this.getClass.getClassLoader.loadClass("cbt.NailgunLauncher")
diff --git a/stage1/cbt.scala b/stage1/cbt.scala
index b97ad44..8cba9df 100644
--- a/stage1/cbt.scala
+++ b/stage1/cbt.scala
@@ -62,6 +62,7 @@ object `package`{
       file.delete
     }
 
+    def listOrFail: Seq[File] = Option( file.listFiles ).getOrElse( throw new Exception( "no such file: " + file ) ).toVector
     def listRecursive: Seq[File] = {
       file +: (
         if( file.isDirectory ) file.listFiles.flatMap(_.listRecursive).toVector else Seq[File]()
diff --git a/stage2/BasicBuild.scala b/stage2/BasicBuild.scala
index 491cdba..fcda629 100644
--- a/stage2/BasicBuild.scala
+++ b/stage2/BasicBuild.scala
@@ -96,7 +96,7 @@ trait BaseBuild extends BuildInterface with DependencyImplementation with SbtDep
   def sources: Seq[File] = (
     Seq(defaultSourceDirectory)
     ++ generatedSources
-    ++ projectDirectory.listFiles.toVector.filter(sourceFileFilter)
+    ++ projectDirectory.listOrFail.toVector.filter(sourceFileFilter)
   )
 
   /** Which file endings to consider being source files. */
@@ -130,7 +130,7 @@ trait BaseBuild extends BuildInterface with DependencyImplementation with SbtDep
   def localJars: Seq[File] =
     Seq(projectDirectory ++ "/lib")
       .filter(_.exists)
-      .flatMap(_.listFiles)
+      .flatMap(_.listOrFail)
       .filter(_.toString.endsWith(".jar"))
 
   override def dependencyClasspath : ClassPath = super.dependencyClasspath
diff --git a/stage2/Lib.scala b/stage2/Lib.scala
index bb59604..04e68f1 100644
--- a/stage2/Lib.scala
+++ b/stage2/Lib.scala
@@ -202,7 +202,7 @@ final class Lib(val logger: Logger) extends Stage1Lib(logger){
     def depthFirstFileStream(file: File): Vector[File] = {
       (
         if (file.isDirectory) {
-          file.listFiles.toVector.flatMap(depthFirstFileStream(_))
+          file.listOrFail.toVector.flatMap(depthFirstFileStream(_))
         } else Vector()
       ) :+ file
     }
-- 
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