Null ref - resolve refs pull request 2445

Error while getting references
System.NullReferenceException: Object reference not set to an instance of an object
  at MonoDevelop.Core.Assemblies.AssemblyContext.NormalizeAsmName (System.String name) [0x00000] in /Users/builder/data/lanes/5681/4526bf19/source/monodevelop/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Assemblies/AssemblyContext.cs:288 
  at MonoDevelop.Core.Assemblies.AssemblyContext.GetAssemblyLocation (System.String assemblyName, System.String package, MonoDevelop.Core.Assemblies.TargetFramework fx) [0x00006] in /Users/builder/data/lanes/5681/4526bf19/source/monodevelop/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Assemblies/AssemblyContext.cs:396 
  at MonoDevelop.Core.Assemblies.ComposedAssemblyContext.GetAssemblyLocation (System.String assemblyName, System.String package, MonoDevelop.Core.Assemblies.TargetFramework fx) [0x00016] in /Users/builder/data/lanes/5681/4526bf19/source/monodevelop/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Assemblies/ComposedAssemblyContext.cs:187 
  at MonoDevelop.Core.Assemblies.ComposedAssemblyContext.GetAssemblyLocation (System.String assemblyName, MonoDevelop.Core.Assemblies.TargetFramework fx) [0x00000] in /Users/builder/data/lanes/5681/4526bf19/source/monodevelop/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Assemblies/ComposedAssemblyContext.cs:181 
  at MonoDevelop.Projects.DotNetProject+<GetReferencedAssembliesDeprecated>d__104.MoveNext () [0x00158] in /Users/builder/data/lanes/5681/4526bf19/source/monodevelop/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/DotNetProject.cs:953 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/exceptionservices/exceptionservicescommon.cs:152 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00037] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:187 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x00028] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:156 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x00008] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:128 
  at System.Runtime.CompilerServices.TaskAwaiter`1[TResult].GetResult () [0x00000] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:357 
  at MonoDevelop.Projects.DotNetProject+<OnGetReferencesDeprecated>d__109.MoveNext () [0x00024] in /Users/builder/data/lanes/5681/4526bf19/source/monodevelop/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/DotNetProject.cs:1091 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/exceptionservices/exceptionservicescommon.cs:152 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00037] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:187 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x00028] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:156 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x00008] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:128 
  at System.Runtime.CompilerServices.TaskAwaiter`1[TResult].GetResult () [0x00000] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:357 
  at MonoDevelop.Projects.DotNetProject+<OnGetReferences>d__108.MoveNext () [0x00045] in /Users/builder/data/lanes/5681/4526bf19/source/monodevelop/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/DotNetProject.cs:1070 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/exceptionservices/exceptionservicescommon.cs:152 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00037] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:187 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x00028] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:156 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x00008] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:128 
  at System.Runtime.CompilerServices.TaskAwaiter`1[TResult].GetResult () [0x00000] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:357 
  at MonoDevelop.Projects.DotNetProject+<>c__DisplayClass99_0+<<GetReferences>b__0>d.MoveNext () [0x00034] in /Users/builder/data/lanes/5681/4526bf19/source/monodevelop/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/DotNetProject.cs:884 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/exceptionservices/exceptionservicescommon.cs:152 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00037] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:187 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x00028] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:156 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x00008] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:128 
  at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1+ConfiguredTaskAwaiter[TResult].GetResult () [0x00000] in /Users/builder/data/lanes/5533/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:535 
  at MonoDevelop.Ide.TypeSystem.MonoDevelopWorkspace+<CreateReferences>d__64.MoveNext () [0x000e9] in /Users/builder/data/lanes/5681/4526bf19/source/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.TypeSystem/MonoDevelopWorkspace.cs:656