Backport #974 (#994)

* Backport 5f9d89a

* Fix async abuse

* Add semicolon

Author: rjmholt

src/PowerShellEditorServices.Protocol/Server/LanguageServer.cs

@@ -1379,6 +1379,12 @@ protected async Task HandleDocumentFormattingRequest(
             DocumentFormattingParams formattingParams,
             RequestContext<TextEdit[]> requestContext)
         {
+            if (this.editorSession.AnalysisService == null)
+            {
+                await requestContext.SendError("Script analysis is not enabled in this session");
+                return;
+            }
+
             var result = await Format(
                 formattingParams.TextDocument.Uri,
                 formattingParams.options,
@@ -1398,6 +1404,12 @@ protected async Task HandleDocumentRangeFormattingRequest(
             DocumentRangeFormattingParams formattingParams,
             RequestContext<TextEdit[]> requestContext)
         {
+            if (this.editorSession.AnalysisService == null)
+            {
+                await requestContext.SendError("Script analysis is not enabled in this session");
+                return;
+            }
+
             var result = await Format(
                 formattingParams.TextDocument.Uri,
                 formattingParams.Options,