On setting negative 'Branches-Size' in Behaviour Parameters MLAgents-Component, console flooded with 'Array size must be non-negative' errors. Refer attached video.

Steps to repro:
1. Create a new Project
2. Package Manager > MLAgents > Install.
3. Hierarchy > Create a Cube > Inspector
4. Cube > Add Component > ML-Agents >Behaviour Parameters
5. Vector Action > Branches Size > Drag Mouse to set negative value.

Actual Result:
Console flooded with 'Array size must be non-negative' errors, On setting negative 'Branches-Size' value.

Expected Result:
No errors in the console and Setting a negative value for 'Branches-Size' should be restricted.

Reproducible in:
2021.1.0a7, 2020.2.0b13, 2020.1.12f1, 2019.4.14f1, 2018.4.29f1 with package version (1.0.6-1.0.2)

Environment:
Windows10 and macOS 10.15

Stack trace:
Array size must be non-negative.
UnityEditor.SerializedProperty:set_arraySize(Int32)
Unity.MLAgents.Editor.BrainParametersDrawer:DrawDiscreteVectorAction(Rect, SerializedProperty) (at Library/PackageCache/com.unity.ml-agents@1.0.2/Editor/BrainParametersDrawer.cs:160)
Unity.MLAgents.Editor.BrainParametersDrawer:DrawVectorAction(Rect, SerializedProperty) (at Library/PackageCache/com.unity.ml-agents@1.0.2/Editor/BrainParametersDrawer.cs:114)
Unity.MLAgents.Editor.BrainParametersDrawer:OnGUI(Rect, SerializedProperty, GUIContent) (at Library/PackageCache/com.unity.ml-agents@1.0.2/Editor/BrainParametersDrawer.cs:44)
UnityEditor.EditorGUILayout:PropertyField(SerializedProperty, Boolean, GUILayoutOption\[])
Unity.MLAgents.Editor.BehaviorParametersEditor:OnInspectorGUI() (at Library/PackageCache/com.unity.ml-agents@1.0.2/Editor/BehaviorParametersEditor.cs:40)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)