Added null check

Author: dkattan

src/PowerShellEditorServices/Services/TextDocument/Handlers/CompletionHandler.cs

@@ -1,14 +1,6 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Management.Automation;
-using System.Text;
-using System.Text.RegularExpressions;
-using System.Threading;
-using System.Threading.Tasks;
 using Microsoft.Extensions.Logging;
 using Microsoft.PowerShell.EditorServices.Services;
 using Microsoft.PowerShell.EditorServices.Services.PowerShell;
@@ -20,6 +12,14 @@
 using OmniSharp.Extensions.LanguageServer.Protocol.Client.Capabilities;
 using OmniSharp.Extensions.LanguageServer.Protocol.Document;
 using OmniSharp.Extensions.LanguageServer.Protocol.Models;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Management.Automation;
+using System.Text;
+using System.Text.RegularExpressions;
+using System.Threading;
+using System.Threading.Tasks;
 
 namespace Microsoft.PowerShell.EditorServices.Handlers
 {
@@ -215,7 +215,7 @@ internal async Task<CompletionResults> GetCompletionsInFileAsync(
                 _logger,
                 cancellationToken).ConfigureAwait(false);
 
-            if (result.CompletionMatches.Count == 0)
+            if (result is null || result.CompletionMatches.Count is 0)
             {
                 return new CompletionResults(IsIncomplete: true, Array.Empty<CompletionItem>());
             }