Steps to reproduce this issue:

-Open the attached project
-Open the coffeeIpsum scene.
-Press play
-The debug log should read the text file and have the "coffeeIpsum" text.
-Stop the scene.
-Build the Asset Bundles from the Menu: (AssetBundles->Create->CreateNewAssetDatabase)
-Open Script ReadCoffeeIpsum.cs
-Make a minor change (like adding a Debug.Log to the start method)
-Save the file
-Switch back into Unity
-You should now be getting the error message:

Assets/Scripts/ReadCoffeeIpsum.cs(39,55): error CS0117: `System.IO.File' does not contain a definition for `ReadAllText'

This error will be shown until you delete library folder and open project again