Fix test failures

src/System.Management.Automation/engine/MshCommandRuntime.cs

@@ -3732,7 +3732,7 @@ internal void SetVariableListsInPipe()
         {
             Diagnostics.Assert(_thisCommand is PSScriptCmdlet, "this is only done for script cmdlets");
 
-            if (_outVarList != null && !OutputPipe.NullPipe)
+            if (_outVarList != null && !OutputPipe.IgnoreOutVariableList)
             {
                 // A null pipe is used when executing the 'Clean' block of a PSScriptCmdlet.
                 // In such a case, we don't capture output to the out variable list.
@@ -3775,7 +3775,7 @@ internal void RemoveVariableListsInPipe()
         {
             // Diagnostics.Assert(thisCommand is PSScriptCmdlet, "this is only done for script cmdlets");
 
-            if (_outVarList != null)
+            if (_outVarList != null && !OutputPipe.IgnoreOutVariableList)
             {
                 this.OutputPipe.RemoveVariableList(VariableStreamKind.Output, _outVarList);
             }

src/System.Management.Automation/engine/Pipe.cs

@@ -109,6 +109,11 @@ public override string ToString()
         /// </summary>
         internal int OutBufferCount { get; set; } = 0;
 
+        /// <summary>
+        /// Gets whether the out variable list should be ignored.
+        /// </summary>
+        internal bool IgnoreOutVariableList { get; set; }
+
         /// <summary>
         /// If true, then all input added to this pipe will simply be discarded...
         /// </summary>

src/System.Management.Automation/engine/pipeline.cs

@@ -7,7 +7,6 @@
 using System.Management.Automation.Tracing;
 using System.Reflection;
 using System.Runtime.ExceptionServices;
-using System.Runtime.InteropServices;
 using Microsoft.PowerShell.Telemetry;
 
 using Dbg = System.Management.Automation.Diagnostics;
@@ -1288,6 +1287,7 @@ private void DisposeCommands()
                         // If Dispose throws an exception, record it as a pipeline failure and continue disposing cmdlets.
                         try
                         {
+                            commandProcessor.CommandRuntime.RemoveVariableListsInPipe();
                             commandProcessor.Dispose();
                         }
                         // The only vaguely plausible reason for a failure here is an exception in Command.Dispose.

src/System.Management.Automation/engine/runtime/CompiledScriptBlock.cs

@@ -2319,9 +2319,15 @@ internal override void DoCleanResource()
         {
             if (_scriptBlock.HasCleanupBlock && _anyClauseExecuted)
             {
-                // The 'Clean' block doesn't write to pipeline.
+                // The 'Clean' block doesn't write any output to pipeline, so we use a 'NullPipe' here and
+                // disallow the output to be collected by an 'out' variable. However, the error, warning,
+                // and information records should still be collectable by the corresponding variables.
                 Pipe oldOutputPipe = _commandRuntime.OutputPipe;
-                _functionContext._outputPipe = _commandRuntime.OutputPipe = new Pipe { NullPipe = true };
+                _functionContext._outputPipe = _commandRuntime.OutputPipe = new Pipe
+                {
+                    NullPipe = true,
+                    IgnoreOutVariableList = true,
+                };
 
                 try
                 {