small fixes

Assets/Engine/Runtime/Measurements/Measure.cs

@@ -26,7 +26,7 @@ namespace EscapeRoomEngine.Engine.Runtime.Measurements
         /// The average time to solve a specific puzzle.
         /// </summary>
         public static float AverageTime(PuzzleModuleDescription puzzle) =>
-            PuzzleStorage.Instance.Load(puzzle).AverageTimeToSolve;
+            PuzzleStorage.Instance.LoadOrNew(puzzle).AverageTimeToSolve;
         /// <summary>
         /// The average time to solve a group of puzzles.
         /// </summary>
@@ -42,7 +42,7 @@ namespace EscapeRoomEngine.Engine.Runtime.Measurements
         /// Estimate the time a specific puzzle will take to be solved by the current player.
         /// </summary>
         public static float EstimateTime(PuzzleModuleDescription puzzle) =>
-            PuzzleStorage.Instance.Load(puzzle).EstimateTimeToSolve(SessionPercentile());
+            PuzzleStorage.Instance.LoadOrNew(puzzle).EstimateTimeToSolve(SessionPercentile());
         /// <summary>
         /// Estimate the time a group of puzzles will take to be solved by the current player.
         /// </summary>

Assets/Engine/Runtime/Measurements/PlanResult.cs

@@ -26,7 +26,7 @@ namespace EscapeRoomEngine.Engine.Runtime.Measurements
         public PlanResult(float targetTime, float sectionPercentile, float timeEstimation)
         {
             TargetTime = targetTime;
-            SectionPercentile = sectionPercentile;
+            SectionPercentile = float.IsNaN(sectionPercentile) ? 0.5f : sectionPercentile;
             TimeEstimation = timeEstimation;
         }
     }

Assets/Engine/Runtime/Measurements/PuzzleStorage.cs

@@ -88,7 +88,7 @@ namespace EscapeRoomEngine.Engine.Runtime.Measurements
         /// Create a new puzzle for a specific description and store it in the database.
         /// </summary>
         /// <remarks>This requires that the puzzle does not yet exist in the database.</remarks>
-        private Puzzle New(PuzzleModuleDescription puzzle)
+        public Puzzle New(PuzzleModuleDescription puzzle)
         {
             Puzzle created = null;
             
@@ -100,7 +100,7 @@ namespace EscapeRoomEngine.Engine.Runtime.Measurements
         /// <summary>
         /// Load a specific puzzle from the database or create it if it wasn't found.
         /// </summary>
-        private Puzzle LoadOrNew(PuzzleModuleDescription puzzle) => _realm.Find<Puzzle>(puzzle.Id) ?? New(puzzle);
+        public Puzzle LoadOrNew(PuzzleModuleDescription puzzle) => _realm.Find<Puzzle>(puzzle.Id) ?? New(puzzle);
 
         /// <summary>
         /// Load a specific puzzle from the database.
@@ -136,9 +136,10 @@ namespace EscapeRoomEngine.Engine.Runtime.Measurements
                 session.PuzzlesSolved.Add(found);
                 
                 // add plan result to session
+                var percentile = found.Distribution.Cumulative(measurement.Time);
                 session.PlanResults.Add(new PlanResult(
                     GameControl.Instance.TargetTime,
-                    found.Distribution.Cumulative(measurement.Time),
+                    percentile,
                     GameControl.Instance.EstimatedTime));
             });
         }

Assets/Engine/Runtime/Modules/ModuleState.cs

@@ -5,6 +5,7 @@ namespace EscapeRoomEngine.Engine.Runtime.Modules
     /// <summary>
     /// An abstract module state. Example implementations are <see cref="DoorState"/> and <see cref="PuzzleState"/>.
     /// </summary>
+    [SelectionBase]
     public abstract class ModuleState : MonoBehaviour
     {
         [Tooltip("The size of this module in meters.")]

Assets/Engine/Runtime/Modules/PuzzleState.cs

@@ -32,7 +32,6 @@ namespace EscapeRoomEngine.Engine.Runtime.Modules
     /// <summary>
     /// The <see cref="ModuleState"/> of a <see cref="PuzzleModule"/>. Handles all events that can occur for a door.
     /// </summary>
-    [SelectionBase]
     public class PuzzleState : ModuleState
     {
         /// <summary>

Assets/Engine/Runtime/Utilities/Probability.cs

@@ -29,7 +29,7 @@ namespace EscapeRoomEngine.Engine.Runtime.Utilities
         public NormalDistribution(float[] samples) : this()
         {
             μ = Probability.Mean(samples);
-            σ = Probability.StandardDeviation(samples, μ);
+            σ = samples.Length == 0 ? 1.0f : Probability.StandardDeviation(samples, μ);
         }
 
         /// <summary>