Give error instead of crashing if WSMan client lib not available (#4387)

src/System.Management.Automation/engine/remoting/fanin/WSManTransportManager.cs

@@ -2597,7 +2597,15 @@ namespace System.Management.Automation.Remoting.Client
 #endif
 
                 _handle = IntPtr.Zero;
-                ErrorCode = WSManNativeApi.WSManInitialize(WSManNativeApi.WSMAN_FLAG_REQUESTED_API_VERSION_1_1, ref _handle);
+
+                try
+                {
+                    ErrorCode = WSManNativeApi.WSManInitialize(WSManNativeApi.WSMAN_FLAG_REQUESTED_API_VERSION_1_1, ref _handle);
+                }
+                catch (DllNotFoundException)
+                {
+                    throw new PSRemotingTransportException(RemotingErrorIdStrings.WSManClientDllNotAvailable);
+                }
 
                 // input / output streams common to all connections
                 _inputStreamSet = new WSManNativeApi.WSManStreamIDSet_ManToUn(

src/System.Management.Automation/resources/RemotingErrorIdStrings.resx

@@ -1636,7 +1636,10 @@ All WinRM sessions connected to Windows PowerShell session configurations, such
   <data name="InvalidRoleCapabilityFileExtension" xml:space="preserve">
     <value>The provided role capability file {0} does not have the required .psrc extension.</value>
   </data>
-  <data name="SSHAbruptlyTerminated" >
+  <data name="SSHAbruptlyTerminated" xml:space="preserve">
     <value>The SSH transport process has abruptly terminated causing this remote session to break.</value>
   </data>
+  <data name="WSManClientDllNotAvailable" xml:space="preserve">
+    <value>This parameter set requires WSMan, and no supported WSMan client library was found. WSMan is either not installed or unavailable for this system.</value>
+  </data>
 </root>