Code highlighting breaks because of the language header

[tkapustina]

STR:

1. Open a feature file
2. Add # language: 


ACTUAL:

https://youtrack.jetbrains.com/issue/DEXP-592129

Incremental reparse Index and length must refer to a location within the string. Parameter name: length
JetBrains Rider 2021.2 Build RD-212.4047.84 Date 2021-06-10T05:39:18.045+0000

--- EXCEPTION #1/3 [ArgumentOutOfRangeException]
Message = “Index and length must refer to a location within the string.”
ExceptionPath = Root.InnerException.InnerException
ClassName = System.ArgumentOutOfRangeException
HResult = COR_E_ARGUMENTOUTOFRANGE=80131502
Source = mscorlib
ParamName = length

StackTraceString = “
at System.String.Substring(Int32 startIndex, Int32 length)
at ReSharperPlugin.SpecflowRiderPlugin.Psi.GherkinKeywordProvider.GetKeywordsList(String language) in D:\a\SpecFlow.Rider\SpecFlow.Rider\src\dotnet\ReSharperPlugin.SpecflowRiderPlugin\Psi\GherkinKeywordProvider.cs:line 76
at ReSharperPlugin.SpecflowRiderPlugin.Psi.GherkinKeywordProvider.GetAllKeywords(String language) in D:\a\SpecFlow.Rider\SpecFlow.Rider\src\dotnet\ReSharperPlugin.SpecflowRiderPlugin\Psi\GherkinKeywordProvider.cs:line 31
at ReSharperPlugin.SpecflowRiderPlugin.Psi.GherkinLexer.UpdateLanguage(String language) in D:\a\SpecFlow.Rider\SpecFlow.Rider\src\dotnet\ReSharperPlugin.SpecflowRiderPlugin\Psi\GherkinLexer.cs:line 56
at ReSharperPlugin.SpecflowRiderPlugin.Psi.GherkinLexer.Advance() in D:\a\SpecFlow.Rider\SpecFlow.Rider\src\dotnet\ReSharperPlugin.SpecflowRiderPlugin\Psi\GherkinLexer.cs:line 174
at JetBrains.ReSharper.Psi.Parsing.TokenBuffer.ReScanUpToEnd(ILexer lexer)
at JetBrains.ReSharper.Psi.Files.CachedPsiFile.GetIncrementalReparseResult(TokenBuffer oldTokenBuffer, IBuffer newBuffer, ISecondaryRangeTransla

[tkapustina]

One more example

Should it be highlighted as an error?

[nemesv]

Fixed in version 1.8.0.

[tkapustina]

Verified.

I'm not sure that language header should be highlighted too, because it's a proper line.
And it would be cool to suggest a quick fix to change the language.