Reproduction steps:
1. Download user's project and open in Unity
2. Select SparkTools > Settings > Builder
3. Platform list should contain only the installed platforms (remove them with an 'X' and add them from the drop-down)
4. Target platform is chosen by the green circle and it cannot be first or the last
5. Press "Build All"

Expected: no errors in the console
Actual: error appears in the console

Reproduced on: 2018.1.0b1; 2018.1.0f2; 2018.2.0b3

Note: error:
"MissingReferenceException: The object of type 'BuildReport' has been destroyed but you are still trying to access it.
Your script should either check if it is null or you should not destroy the object.
UnityEditor.Build.Reporting.BuildReport.get_summary ()
SparkTools.Builder.BuildMultiple (SparkTools.BuilderSettings settings, System.Int32[] indexes) (at Assets/SparkTools/builder/Builder/Editor/Scripts/Builder.cs:141)
SparkTools.Builder.BuildAll () (at Assets/SparkTools/builder/Builder/Editor/Scripts/Builder.cs:84)
SparkTools.BuilderSettingsEditor.OnInspectorGUI () (at Assets/SparkTools/builder/Builder/Editor/Scripts/BuilderSettingsEditor.cs:247)
UnityEditor.InspectorWindow.DrawEditor (UnityEditor.Editor[] editors, Int32 editorIndex, Boolean rebuildOptimizedGUIBlock, System.Boolean& showImportedObjectBarNext, UnityEngine.Rect& importedObjectBarRect) (at C:/buildslave/unity/build/Editor/Mono/Inspector/InspectorWindow.cs:1374)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)"