make component inventory components array even more lazy

allow a component inventory to define its inventory size from nbt even after the components array has been accessed. The array will appear to be size zero until initialized

closes #2522

src/main/scala/li/cil/oc/common/inventory/ComponentInventory.scala

@@ -17,7 +17,16 @@ import scala.collection.convert.WrapAsScala._
 import scala.collection.mutable
 
 trait ComponentInventory extends Inventory with network.Environment {
-  lazy val components = Array.fill[Option[ManagedEnvironment]](getSizeInventory)(None)
+  private var _components: Array[Option[ManagedEnvironment]] = _
+  protected var isSizeInventoryReady: Boolean = true
+
+  def components: Array[Option[ManagedEnvironment]] = {
+    if (_components == null && isSizeInventoryReady) {
+      _components = Array.fill[Option[ManagedEnvironment]](getSizeInventory)(None)
+    }
+    if (_components == null) Array[Option[ManagedEnvironment]]() else _components
+  }
+
   protected val updatingComponents = mutable.ArrayBuffer.empty[ManagedEnvironment]
 
   // ----------------------------------------------------------------------- //
@@ -99,6 +108,13 @@ trait ComponentInventory extends Inventory with network.Environment {
     for (slot <- 0 until getSizeInventory) {
       val stack = getStackInSlot(slot)
       if (stack != null) {
+        if (slot >= components.length) {
+          // isSizeInventoryReady was added to resolve issues where an inventory was used before its
+          // nbt data had been parsed. See https://github.com/MightyPirates/OpenComputers/issues/2522
+          // If this error is hit again, perhaps another subtype needs to handle nbt loading like Case does
+          OpenComputers.log.error(s"ComponentInventory components length ${components.length} does not accommodate inventory size ${getSizeInventory}")
+          return
+        } else {
           components(slot) match {
             case Some(component) =>
               // We're guaranteed to have a driver for entries.
@@ -108,6 +124,7 @@ trait ComponentInventory extends Inventory with network.Environment {
         }
       }
     }
+  }
 
   // ----------------------------------------------------------------------- //
 

src/main/scala/li/cil/oc/common/tileentity/Case.scala

@@ -25,7 +25,12 @@ import net.minecraftforge.common.util.ForgeDirection
 import scala.collection.convert.WrapAsJava._
 
 class Case(var tier: Int) extends traits.PowerAcceptor with traits.Computer with traits.Colored with internal.Case with DeviceInfo {
-  def this() = this(0)
+  def this() = {
+    this(0)
+    // If no tier was defined when constructing this case, then we don't yet know the inventory size
+    // this is set back to true when the nbt data is loaded
+    isSizeInventoryReady = false
+  }
 
   // Used on client side to check whether to render disk activity/network indicators.
   var lastFileSystemAccess = 0L
@@ -78,6 +83,7 @@ class Case(var tier: Int) extends traits.PowerAcceptor with traits.Computer with
     tier = nbt.getByte(Settings.namespace + "tier") max 0 min 3
     color = Color.byTier(tier)
     super.readFromNBTForServer(nbt)
+    isSizeInventoryReady = true
   }
 
   override def writeToNBTForServer(nbt: NBTTagCompound) {