NRE for naming conventions field

[Vannevelj]

Stacktrace:

System.NullReferenceException : Object reference not set to an instance of an object.
   at async VSDiagnostics.Utilities.RenameHelper.RenameSymbolAsync(<Unknown Parameters>)
   at async VSDiagnostics.Diagnostics.General.NamingConventions.NamingConventionsCodeFix.RenameAsync(<Unknown Parameters>)
   at async Microsoft.CodeAnalysis.CodeActions.CodeAction.ComputeOperationsAsync(<Unknown Parameters>)
   at async Microsoft.CodeAnalysis.CodeActions.CodeAction.ComputePreviewOperationsAsync(<Unknown Parameters>)
   at async Microsoft.CodeAnalysis.CodeActions.CodeAction.GetPreviewOperationsAsync(<Unknown Parameters>)
   at async Microsoft.CodeAnalysis.Editor.Implementation.Suggestions.SuggestedAction.GetPreviewResultAsync(<Unknown Parameters>)
   at async Microsoft.CodeAnalysis.Editor.Implementation.Suggestions.SuggestedActionWithNestedFlavors.<>c__DisplayClass11_0.<GetPreviewAsync>b__0(<Unknown Parameters>)
   at async Microsoft.CodeAnalysis.Extensions.IExtensionManagerExtensions.PerformFunctionAsync[T](<Unknown Parameters>)

Code:

    private readonly IListingService [C]listingService;

    public CategoryController(IListingService listingService)
    {
        this.listingService = listingService;
    }

Cursor is placed at [C]