Build error with solutions for VB code

[bertiewooster]

I have an existing solution with several projects, some C# and some VB; the solution itself builds (compiles) fine from Visual Studio 2022. When I run docfx 2.59.0.0 with "files": [//"src/**.csproj"] in docfx.json it builds fine, but only documents the C# code. But when I try to document the VB code using "files": ["**/*.sln"] or "files": [ "src/**.sln"], I get an error on some solutions, the crux of which is Value cannot be null. Parameter name: text. What would case that error?

Here's the full error output:

Error:Error extracting metadata for MySolution.sln,Reference.sln: System.ArgumentNullException: Value cannot be null.
Parameter name: text
   at Microsoft.CodeAnalysis.Text.SourceText.From(String text, Encoding encoding, SourceHashAlgorithm checksumAlgorithm)
   at Microsoft.CodeAnalysis.CSharp.SyntaxFactory.MakeSourceText(String text, Int32 offset)
   at Microsoft.CodeAnalysis.CSharp.SyntaxFactory.ParseName(String text, Int32 offset, Boolean consumeFullText)
   at Microsoft.DocAsCode.Metadata.ManagedReference.CSYamlModelGenerator.GetPropertySyntax(IPropertySymbol symbol, IFilterVisitor filterVisitor)
   at Microsoft.DocAsCode.Metadata.ManagedReference.CSYamlModelGenerator.GetSyntaxContent(MemberType typeKind, ISymbol symbol, SymbolVisitorAdapter adapter)
   at Microsoft.DocAsCode.Metadata.ManagedReference.CompositeYamlModelGenerator.GenerateSyntax(MemberType type, ISymbol symbol, SyntaxDetail syntax, SymbolVisitorAdapter adapter)
   at Microsoft.DocAsCode.Metadata.ManagedReference.SymbolVisitorAdapter.VisitProperty(IPropertySymbol symbol)
   at Microsoft.DocAsCode.Metadata.ManagedReference.SymbolVisitorAdapter.VisitNamedType(INamedTypeSymbol symbol)
   at Microsoft.DocAsCode.Metadata.ManagedReference.SymbolVisitorAdapter.VisitDescendants[T](IEnumerable`1 children, Func`2 getChildren, Func`2 filter)
   at Microsoft.DocAsCode.Metadata.ManagedReference.SymbolVisitorAdapter.VisitNamespace(INamespaceSymbol symbol)
   at Microsoft.DocAsCode.Metadata.ManagedReference.SymbolVisitorAdapter.VisitDescendants[T](IEnumerable`1 children, Func`2 getChildren, Func`2 filter)
   at Microsoft.DocAsCode.Metadata.ManagedReference.SymbolVisitorAdapter.VisitAssembly(IAssemblySymbol symbol)
   at Microsoft.DocAsCode.Metadata.ManagedReference.RoslynMetadataExtractor.Extract(ExtractMetadataOptions options)
   at Microsoft.DocAsCode.Metadata.ManagedReference.ExtractMetadataWorker.GetMetadataFromProjectLevelCache(IBuildController controller, IInputParameters key)
   at Microsoft.DocAsCode.Metadata.ManagedReference.ExtractMetadataWorker.<SaveAllMembersFromCacheAsync>d__13.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.DocAsCode.Metadata.ManagedReference.ExtractMetadataWorker.<ExtractMetadataAsync>d__11.MoveNext()
        29 Warning(s)
        1 Error(s)