ml-agents/unity-environment/Assets/ML-Agents/Scripts/UnityAgentsException.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

using System;
[System.Serializable]
/// Contains exceptions specific to ML-Agents.
public class UnityAgentsException : System.Exception
{
    /// When a UnityAgentsException is called, the timeScale is set to 0.
    /// The simulation will end since no steps will be taken.
    public UnityAgentsException(string message) : base(message)
    {
        Time.timeScale = 0f;
    }

    /// A constructor is needed for serialization when an exception propagates 
    /// from a remoting server to the client. 
    protected UnityAgentsException(System.Runtime.Serialization.SerializationInfo info,
        System.Runtime.Serialization.StreamingContext context)
    { }
}