From cec4c9ec3ae85d9e0f4f50d32b703f3200182b76 Mon Sep 17 00:00:00 2001
From: Adam Driscoll <adamdriscoll@users.noreply.github.com>
Date: Mon, 16 Dec 2019 08:07:47 -0700
Subject: [PATCH] Fixes #1369

---
 .../Execution/SessionDriveProvider.cs         | 35 +++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/src/UniversalDashboard/Execution/SessionDriveProvider.cs b/src/UniversalDashboard/Execution/SessionDriveProvider.cs
index 803d304c..9e5c699c 100644
--- a/src/UniversalDashboard/Execution/SessionDriveProvider.cs
+++ b/src/UniversalDashboard/Execution/SessionDriveProvider.cs
@@ -57,6 +57,11 @@ private string SessionId
         private HostState HostState => Host.PrivateData.BaseObject as HostState;
         protected override void GetItem(string name)
         {
+            if (HostState?.EndpointService?.SessionManager == null)
+            {
+                throw new Exception("You cannot call the $Session provider outside of an endpoint.");
+            }
+            
             if (HostState.EndpointService.SessionManager.SessionExists(SessionId))
             {
                 var value = HostState.EndpointService.SessionManager.GetSession(SessionId).GetVariableValue(name);
@@ -69,6 +74,11 @@ protected override void GetItem(string name)
 
         protected override void NewItem(string path, string itemTypeName, object newItemValue)
         {
+            if (HostState?.EndpointService?.SessionManager == null)
+            {
+                throw new Exception("You cannot call the $Session provider outside of an endpoint.");
+            }
+
             if (HostState.EndpointService.SessionManager.SessionExists(SessionId))
             {
                 HostState.EndpointService.SessionManager.GetSession(SessionId).SetVariable(path, newItemValue);
@@ -77,6 +87,11 @@ protected override void NewItem(string path, string itemTypeName, object newItem
 
         protected override void SetItem(string name, object value)
         {
+            if (HostState?.EndpointService?.SessionManager == null)
+            {
+                throw new Exception("You cannot call the $Session provider outside of an endpoint.");
+            }
+
             if (HostState.EndpointService.SessionManager.SessionExists(SessionId))
             {
                 HostState.EndpointService.SessionManager.GetSession(SessionId).SetVariable(name, value);
@@ -85,6 +100,11 @@ protected override void SetItem(string name, object value)
 
         protected override bool ItemExists(string path)
         {
+            if (HostState?.EndpointService?.SessionManager == null)
+            {
+                throw new Exception("You cannot call the $Session provider outside of an endpoint.");
+            }
+
             if (HostState.EndpointService.SessionManager.SessionExists(SessionId))
             {
                 return HostState.EndpointService.SessionManager.GetSession(SessionId).SessionVariables.ContainsKey(path.ToLower());
@@ -99,6 +119,11 @@ protected override bool IsValidPath(string path)
 
         public void ClearContent(string path)
         {
+            if (HostState?.EndpointService?.SessionManager == null)
+            {
+                throw new Exception("You cannot call the $Session provider outside of an endpoint.");
+            }
+
             if (HostState.EndpointService.SessionManager.SessionExists(SessionId))
             {
                 HostState.EndpointService.SessionManager.GetSession(SessionId).RemoveVariable(path);
@@ -114,6 +139,11 @@ public IContentReader GetContentReader(string path)
         {
             Logger.Debug($"GetContentReader - {path} ");
 
+            if (HostState?.EndpointService?.SessionManager == null)
+            {
+                throw new Exception("You cannot call the $Session provider outside of an endpoint.");
+            }
+
             if (HostState.EndpointService.SessionManager.SessionExists(SessionId))
             {
                 return new SessionStateReaderWriter(path.ToLower(), HostState.EndpointService.SessionManager.GetSession(SessionId));
@@ -131,6 +161,11 @@ public IContentWriter GetContentWriter(string path)
         {
             Logger.Debug($"GetContentWriter - {path} ");
 
+            if (HostState?.EndpointService?.SessionManager == null)
+            {
+                throw new Exception("You cannot call the $Session provider outside of an endpoint.");
+            }
+
             if (HostState.EndpointService.SessionManager.SessionExists(SessionId))
             {
                 return new SessionStateReaderWriter(path.ToLower(), HostState.EndpointService.SessionManager.GetSession(SessionId));