How to reproduce:
1. Open the attached "1064955_repro.zip" project
2. Open the "Main" scene
3. Enter Play mode
-- Editor crash

Reproducible with - 2018.2.0a3, 2018.2.2f1, 2018.3.0a7
Not reproducible with - 2017.1.5f1, 2017.2.3p2, 2017.4.8f1, 2018.1.9f1, 2018.2.0a2

Notes:
- On versions before the regression, the reproduction steps result in a Console error, that warns about the NullReferenceException.
- The issue occurs on the Build as well.

Stack trace:
(Unity) ImageConversionBindings::LoadImage
(Unity) ImageConversion_CUSTOM_LoadImage
(Mono JIT Code) (wrapper managed-to-native) UnityEngine.ImageConversion:LoadImage (UnityEngine.Texture2D,byte[],bool)
(Mono JIT Code) [C:\buildslave\unity\build\Modules\ImageConversion\ScriptBindings\ImageConversion.bindings.cs:34] UnityEngine.ImageConversion:LoadImage (UnityEngine.Texture2D,byte[])
(Mono JIT Code) [C:\Users\QA Students\Desktop\1064955\Assets\ImageLoader.cs:9] ImageLoader:Start ()
(Mono JIT Code) (wrapper runtime-invoke) object:runtime_invoke_void__this__ (object,intptr,intptr,intptr)
(mono) [c:\buildslave\mono\build\mono\mini\mini.c:4937] mono_jit_runtime_invoke
(mono) [c:\buildslave\mono\build\mono\metadata\object.c:2623] mono_runtime_invoke
(Unity) scripting_method_invoke
(Unity) ScriptingInvocation::Invoke
(Unity) MonoBehaviour::InvokeMethodOrCoroutineChecked
(Unity) MonoBehaviour::InvokeMethodOrCoroutineChecked
(Unity) MonoBehaviour::Start
<...>

Fixed in 2018.3.0a12