Crash from LSR

Hi Chris,
We found there are crash from here
in LSR, DynamicCompilationBase.cs:66

```
AssemblyCsharpFullPath = SessionStateCache.GetOrCreateString(
$"FSR:AssemblyCsharpFullPath",
() => AssetDatabase.FindAssets("Microsoft.CSharp")
.Select(g => new System.IO.FileInfo(UnityEngine.Application.dataPath + "/../" + AssetDatabase.GUIDToAssetPath(g)))
.First(fi => fi.Name.ToLower() == "Microsoft.CSharp.dll".ToLower()).FullName
```
`Sequence contains no matching element

Microsoft.CSharp wont find anything in assets as FSR is in package

We tried this
`() => AssetDatabase.FindAssets("Microsoft.CSharp", new string[]{ "Packages", "Assets"})`

from https://discussions.unity.com/t/assetdatabase-findassets-not-working-for-packages/707087/10

But seems it was not enough and it still can't find it, we're on unity 6.1.14f1

Comienza en DynamicCompilationBase.cs:66 y reproduce el fallo en Unity 6.1.14f1. Inspecciona la búsqueda de AssetDatabase.FindAssets y la ubicación del paquete indicada para Microsoft.CSharp.dll. Se considera terminado cuando el ensamblado se encuentra sin un fallo de „Sequence contains no matching element“ al ejecutarse FastScriptReload.

Escrito por el modelo de indexación a partir del texto del issue.