Protect against missing edges in graph by using map get vs apply

main/src/main/scala/sbt/internal/graph/GraphTransformations.scala

@@ -32,7 +32,7 @@ object GraphTransformations {
     val nodes =
       edges
         .foldLeft(Set.empty[GraphModuleId])((set, edge) => set + edge._1 + edge._2)
-        .map(graph.module)
+        .flatMap(graph.module)
     ModuleGraph(nodes.toSeq, edges)
   }
 

main/src/main/scala/sbt/internal/graph/model.scala

@@ -67,7 +67,7 @@ private[sbt] case class ModuleGraph(nodes: Seq[Module], edges: Seq[Edge]) {
   lazy val modules: Map[GraphModuleId, Module] =
     nodes.map(n => (n.id, n)).toMap
 
-  def module(id: GraphModuleId): Module = modules(id)
+  def module(id: GraphModuleId): Option[Module] = modules.get(id)
 
   lazy val dependencyMap: Map[GraphModuleId, Seq[Module]] =
     createMap(identity)
@@ -81,7 +81,7 @@ private[sbt] case class ModuleGraph(nodes: Seq[Module], edges: Seq[Edge]) {
     val m = new HashMap[GraphModuleId, Set[Module]] with MultiMap[GraphModuleId, Module]
     edges.foreach { entry =>
       val (f, t) = bindingFor(entry)
-      m.addBinding(f, module(t))
+      module(t).foreach(m.addBinding(f, _))
     }
     m.toMap.mapValues(_.toSeq.sortBy(_.id.idString)).toMap.withDefaultValue(Nil)
   }

main/src/main/scala/sbt/internal/graph/rendering/DOT.scala

@@ -31,8 +31,8 @@ object DOT {
       }
     }.sorted.mkString("\n")
 
-    def originWasEvicted(edge: Edge): Boolean = graph.module(edge._1).isEvicted
-    def targetWasEvicted(edge: Edge): Boolean = graph.module(edge._2).isEvicted
+    def originWasEvicted(edge: Edge): Boolean = graph.module(edge._1).exists(_.isEvicted)
+    def targetWasEvicted(edge: Edge): Boolean = graph.module(edge._2).exists(_.isEvicted)
 
     // add extra edges from evicted to evicted-by module
     val evictedByEdges: Seq[Edge] =
@@ -43,13 +43,11 @@ object DOT {
     // remove edges to new evicted-by module which is now replaced by a chain
     // dependend -> [evicted] -> dependee
     val evictionTargetEdges =
-      graph.edges
-        .filter(targetWasEvicted)
-        .map {
-          case (from, evicted) =>
-            (from, evicted.copy(version = graph.module(evicted).evictedByVersion.get))
-        }
-        .toSet
+      graph.edges.collect {
+        case edge @ (from, evicted) if targetWasEvicted(edge) =>
+          // Can safely call `get` as `targetWasEvicted` already proves evicted exists in the graph
+          (from, evicted.copy(version = graph.module(evicted).flatMap(_.evictedByVersion).get))
+      }.toSet
 
     val filteredEdges =
       graph.edges
@@ -58,7 +56,7 @@ object DOT {
     val edges = {
       for (e <- filteredEdges) yield {
         val extra =
-          if (graph.module(e._1).isEvicted)
+          if (graph.module(e._1).exists(_.isEvicted))
             s""" [label="Evicted By" style="$EvictedStyle"]"""
           else ""
         """    "%s" -> "%s"%s""".format(e._1.idString, e._2.idString, extra)

main/src/main/scala/sbt/internal/graph/rendering/Statistics.scala

@@ -28,7 +28,7 @@ object Statistics {
       val directDependencies = graph.dependencyMap(moduleId).filterNot(_.isEvicted).map(_.id)
       val dependencyStats =
         directDependencies.map(statsFor).flatMap(_.transitiveStatsWithSelf).toMap
-      val selfSize = graph.module(moduleId).jarFile.filter(_.exists).map(_.length)
+      val selfSize = graph.module(moduleId).flatMap(_.jarFile).filter(_.exists).map(_.length)
       val numDirectDependencies = directDependencies.size
       val numTransitiveDependencies = dependencyStats.size
       val transitiveSize = selfSize.getOrElse(0L) + dependencyStats