Gracefully handle unavailable TSF from SYSTEM account (#19635)

When run from SYSTEM account TSF seems to be unavailable. The only
missing step to handle that is check during initialization.

Not sure if fail after partial success in `Implementation::Initialize`
should also be gracefully handled.

Closes #19634

Author: SEt-t

src/tsf/Handle.cpp

@@ -12,7 +12,11 @@ Handle Handle::Create()
 {
     Handle handle;
     handle._impl = new Implementation();
-    handle._impl->Initialize();
+    if (!handle._impl->Initialize())
+    {
+        delete handle._impl;
+        handle._impl = nullptr;
+    }
     return handle;
 }
 

src/tsf/Implementation.cpp

@@ -68,9 +68,14 @@ void Implementation::SetDefaultScopeAlphanumericHalfWidth(bool enable) noexcept
     s_wantsAnsiInputScope.store(enable, std::memory_order_relaxed);
 }
 
-void Implementation::Initialize()
+bool Implementation::Initialize()
 {
-    _categoryMgr = wil::CoCreateInstance<ITfCategoryMgr>(CLSID_TF_CategoryMgr, CLSCTX_INPROC_SERVER);
+    _categoryMgr = wil::CoCreateInstanceNoThrow<ITfCategoryMgr>(CLSID_TF_CategoryMgr);
+    if (!_categoryMgr)
+    {
+        return false;
+    }
+
     _displayAttributeMgr = wil::CoCreateInstance<ITfDisplayAttributeMgr>(CLSID_TF_DisplayAttributeMgr);
 
     // There's no point in calling TF_GetThreadMgr. ITfThreadMgr is a per-thread singleton.
@@ -89,6 +94,7 @@ void Implementation::Initialize()
     THROW_IF_FAILED(_contextSource->AdviseSink(IID_ITfTextEditSink, static_cast<ITfTextEditSink*>(this), &_cookieTextEditSink));
 
     THROW_IF_FAILED(_documentMgr->Push(_context.get()));
+    return true;
 }
 
 void Implementation::Uninitialize() noexcept

src/tsf/Implementation.h

@@ -21,7 +21,7 @@ namespace Microsoft::Console::TSF
 
         virtual ~Implementation() = default;
 
-        void Initialize();
+        bool Initialize();
         void Uninitialize() noexcept;
         HWND FindWindowOfActiveTSF() noexcept;
         void AssociateFocus(IDataProvider* provider);