The value unset is not supported by the csharp_style_namespace_declarations option

[flipZomb]

Originally reported at dotnet/format#1926.

Getting the below exception when running "dotnet format" with the following installed :

1. dotnet SDK 7.0.306 (windows x64)
2. C# v2.0.320
3. EditorConfig for VS Code v0.16.4

Going back to dotnet SDK 7.0.203 (windows x64), stops this from happenening (sorry, didn't try the intermediate versions).

Unhandled exception: System.NotSupportedException: Specified method is not supported.
   at Microsoft.CodeAnalysis.CSharp.CodeStyle.CSharpCodeStyleOptions.ParseNamespaceDeclaration(String optionString, CodeStyleOption2`1 default)
   at Microsoft.CodeAnalysis.CSharp.CodeStyle.CSharpCodeStyleOptions.<>c__DisplayClass75_2.<.cctor>b__7(String str)
   at Microsoft.CodeAnalysis.Options.EditorConfigValueSerializer`1.TryParseValue(String value, T& result)
   at Microsoft.CodeAnalysis.Options.EditorConfigValueSerializer`1.Microsoft.CodeAnalysis.Options.IEditorConfigValueSerializer.TryParse(String value, Object& result)
   at Microsoft.CodeAnalysis.Options.DocumentOptionSet.TryGetAnalyzerConfigOption(OptionKey optionKey, Object& value)
   at Microsoft.CodeAnalysis.Options.DocumentOptionSet.GetInternalOptionValue(OptionKey optionKey)
   at Microsoft.CodeAnalysis.Options.OptionSet.Microsoft.CodeAnalysis.Options.IOptionsReader.TryGetOption[T](OptionKey2 optionKey, T& value)
   at Microsoft.CodeAnalysis.Options.Extensions.GetOption[T](IOptionsReader options, Option2`1 option, T defaultValue)
   at Microsoft.CodeAnalysis.CSharp.Formatting.CSharpSyntaxFormattingOptions..ctor(IOptionsReader options, CSharpSyntaxFormattingOptions 
fallbackOptions)
   at Microsoft.CodeAnalysis.CSharp.Formatting.CSharpSyntaxFormatting.GetFormattingOptions(IOptionsReader options, SyntaxFormattingOptions fallbackOptions)
   at Microsoft.CodeAnalysis.Formatting.Formatter.GetFormattingOptionsAsync(Document document, OptionSet optionSet, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Formatting.Formatter.FormatAsync(Document document, IEnumerable`1 spans, OptionSet options, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Tools.Formatters.WhitespaceFormatter.GetFormattedDocument(Document document, OptionSet optionSet, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Tools.Formatters.WhitespaceFormatter.FormatFileAsync(Document document, SourceText sourceText, OptionSet optionSet, AnalyzerConfigOptions analyzerConfigOptions, FormatOptions formatOptions, ILogger logger, CancellationToken cancellationToken)   
   at Microsoft.CodeAnalysis.Tools.Formatters.DocumentFormatter.GetFormattedSourceTextAsync(Document document, OptionSet optionSet, AnalyzerConfigOptions analyzerConfigOptions, FormatOptions formatOptions, ILogger logger, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Tools.Formatters.DocumentFormatter.<>c__DisplayClass8_1.<<FormatFiles>b__0>d.MoveNext()
--- End of stack trace from previous location ---
   at Microsoft.CodeAnalysis.Tools.Formatters.DocumentFormatter.ApplyFileChangesAsync(Solution solution, ImmutableArray`1 formattedDocuments, FormatOptions formatOptions, ILogger logger, List`1 formattedFiles, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Tools.Formatters.DocumentFormatter.FormatAsync(Solution solution, ImmutableArray`1 formattableDocuments, FormatOptions formatOptions, ILogger logger, List`1 formattedFiles, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Tools.CodeFormatter.RunCodeFormattersAsync(Solution solution, ImmutableArray`1 formattableDocuments, FormatOptions formatOptions, ILogger logger, List`1 formattedFiles, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Tools.CodeFormatter.FormatWorkspaceAsync(FormatOptions formatOptions, ILogger logger, CancellationToken cancellationToken, String binaryLogPath)
   at Microsoft.CodeAnalysis.Tools.FormatCommandCommon.FormatAsync(FormatOptions formatOptions, ILogger`1 logger, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Tools.Commands.RootFormatCommand.FormatCommandDefaultHandler.InvokeAsync(InvocationContext context)
   at System.CommandLine.Invocation.InvocationPipeline.<>c__DisplayClass4_0.<<BuildInvocationChain>b__0>d.MoveNext()
--- End of stack trace from previous location ---
   at System.CommandLine.CommandLineBuilderExtensions.<>c__DisplayClass16_0.<<UseParseErrorReporting>b__0>d.MoveNext()
--- End of stack trace from previous location ---
   at System.CommandLine.CommandLineBuilderExtensions.<>c__DisplayClass11_0.<<UseHelp>b__0>d.MoveNext()
--- End of stack trace from previous location ---
   at System.CommandLine.CommandLineBuilderExtensions.<>c__DisplayClass21_0.<<UseVersionOption>b__0>d.MoveNext()
--- End of stack trace from previous location ---
   at System.CommandLine.CommandLineBuilderExtensions.<>c__DisplayClass18_0.<<UseTypoCorrections>b__0>d.MoveNext()
--- End of stack trace from previous location ---
   at System.CommandLine.CommandLineBuilderExtensions.<>c.<<UseSuggestDirective>b__17_0>d.MoveNext()
--- End of stack trace from previous location ---
   at System.CommandLine.CommandLineBuilderExtensions.<>c__DisplayClass15_0.<<UseParseDirective>b__0>d.MoveNext()
--- End of stack trace from previous location ---
   at System.CommandLine.CommandLineBuilderExtensions.<>c.<<RegisterWithDotnetSuggest>b__4_0>d.MoveNext()
--- End of stack trace from previous location ---
   at System.CommandLine.CommandLineBuilderExtensions.<>c__DisplayClass7_0.<<UseExceptionHandler>b__0>d.MoveNext()

.editorconfig contains the following

...
# CSharp formatting rules:
[*.cs]
dotnet_style_object_initializer = false
dotnet_style_collection_initializer = false
csharp_style_namespace_declarations = file_scoped:warning
...
# Ignore paths
[{*_mig?.cs,*_mig??.cs}]
csharp_style_namespace_declarations = unset

[JoeRobich]

After several failed attempts to have GitHub transfer this issue, I am just going to leave this one open. See dotnet/format#1926 for more context.