Ok... either I did it wrong (again), or Maki broke something earlier today? Got this error just after attempting a fresh run to test out your null->0 changes:
1>------ Build started: Project: FF8, Configuration: Debug x64 ------
1> C:/Users/Simplisafe/Source/Repos/MaKiPL/OpenVIII/FF8/Content/Shadow.png
1>C:/Users/Simplisafe/Source/Repos/MaKiPL/OpenVIII/FF8/Content/Shadow.png : error : Importer 'TextureImporter' had unexpected failure!
1> System.DllNotFoundException: Unable to load DLL 'FreeImage': The specified module could not be found. (Exception from HRESULT: 0x8007007E)
1> at FreeImageAPI.FreeImage.GetFileType(String filename, Int32 size)
1> at FreeImageAPI.FreeImage.LoadEx(String filename, FREE_IMAGE_LOAD_FLAGS flags, FREE_IMAGE_FORMAT& format)
1> at Microsoft.Xna.Framework.Content.Pipeline.TextureImporter.Import(String filename, ContentImporterContext context)
1> at Microsoft.Xna.Framework.Content.Pipeline.ContentImporter`1.Microsoft.Xna.Framework.Content.Pipeline.IContentImporter.Import(String filename, ContentImporterContext context)
1> at MonoGame.Framework.Content.Pipeline.Builder.PipelineManager.ProcessContent(PipelineBuildEvent pipelineEvent)
1>C:\Program Files (x86)\MSBuild\MonoGame\v3.0\MonoGame.Content.Builder.targets(84,5): error MSB3073: The command ""C:\Program Files (x86)\MSBuild\MonoGame\v3.0\Tools\MGCB.exe" /quiet /platform:DesktopGL /@:"C:\Users\Simplisafe\Source\Repos\MaKiPL\OpenVIII\FF8\Content\Content.mgcb" /outputDir:"bin\DesktopGL\Content" /intermediateDir:"obj\DesktopGL\Content"" exited with code 1.
========== Build: 0 succeeded or up-to-date, 1 failed, 0 skipped ==========