InitializeOnLoad = System.NullReferenceException

Questions & Answers
1

using UnityEngine;
using UnityEditor;

[InitializeOnLoad]

public class VersionUpdater
{
    static VersionUpdater()
    {
		GameObject.FindGameObjectWithTag("Version").GetComponent<TextMesh>().text = "v"+PlayerSettings.bundleVersion;
    }
}

Gives this ugly error:

*System.NullReferenceException:
at (wrapper managed-to-native) UnityEngine.GameObject:GetComponent (System.Type)
at UnityEngine.GameObject.GetComponent[TextMesh] () [0x00000] in :0
at VersionUpdater…cctor () [0x0000b] in /Users/Luke/Desktop/Unity/Unity Projects/Now You’re Dead/Now You’re Dead/Assets/Editor/VersionUpdater.cs:11
UnityEditor.EditorAssemblies:SetLoadedEditorAssemblies(Assembly)
*

2

It’s because you are trying to get an object which doesn’t exists at that moment.
[InitializeOnLoad] invokes static cctor as soon as possible, i.e. in most cases when Unity starts and no game objects created.