From e4d2f1ab68832df120b137ac722be8b27eca55df Mon Sep 17 00:00:00 2001
From: Kris Borowinski <kris.borowinski@outlook.com>
Date: Sat, 18 May 2024 16:20:58 +0200
Subject: [PATCH] Add null check for $host.UI and its properties to avoid race
 condition (#2383)

---
 src/functions/Output.ps1 | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/functions/Output.ps1 b/src/functions/Output.ps1
index d9df42923..c376e97c6 100644
--- a/src/functions/Output.ps1
+++ b/src/functions/Output.ps1
@@ -1127,7 +1127,8 @@ function Resolve-OutputConfiguration ([PesterConfiguration]$PesterPreference) {
             # https://no-color.org/)
             $PesterPreference.Output.RenderMode = 'Plaintext'
         }
-        elseif (($supportsVT = $host.UI.psobject.Properties['SupportsVirtualTerminal']) -and $supportsVT.Value) {
+        # Null check $host.UI and its properties to avoid race condition when accessing them from multiple threads. https://github.com/pester/Pester/issues/2383
+        elseif ($null -ne $host.UI -and ($hostProperties = $host.UI.psobject.Properties) -and ($supportsVT = $hostProperties['SupportsVirtualTerminal']) -and $supportsVT.Value) {
             $PesterPreference.Output.RenderMode = 'Ansi'
         }
         else {