Update com.unity.ml-agents/Runtime/Sensors/RayPerceptionSensor.cs

Co-authored-by: Chris Elion <chris.elion@unity3d.com>

Author: surfnerd

com.unity.ml-agents/Runtime/Sensors/RayPerceptionSensor.cs

@@ -431,7 +431,7 @@ out DebugDisplayInfo.RayInfo debugRayOut
 
             // Do the cast and assign the hit information for each detectable tag.
             var castHit = false;
-            var hitFraction = float.NaN;
+            var hitFraction = 1.0f;
             GameObject hitObject = null;
 
             if (input.CastType == RayPerceptionCastType.Cast3D)