Fix reference on font asset unload 28ea7f134d

#4059

Source/Engine/Render2D/FontAsset.cpp

@@ -69,6 +69,7 @@ void FontAsset::unload(bool isReloading)
     _fontFile.Release();
     _virtualBold = nullptr;
     _virtualItalic = nullptr;
+    _virtualMSDF = nullptr;
 }
 
 AssetChunksFlag FontAsset::getChunksToPreload() const

Source/Engine/Render2D/FontAsset.h

@@ -182,7 +182,7 @@ public:
     API_FUNCTION() FontAsset* GetItalic();
 
     /// <summary>
-    /// Gets the MSDF version of the font. Returns itself or creates a new virtual font asset using this font but rasterized with MSDF.
+    /// Gets the MSDF version of the font. Returns itself or creates a new virtual font asset using this font but rasterized with Multi-channel Signed Distance Field (MSDF).
     /// </summary>
     /// <returns>The virtual font or this.</returns>
     API_FUNCTION() FontAsset* GetMSDF();