CSC error AD0001 IndexOutOfRangeException

### Description

I get exceptions both in Visual Studio and from CLI

> CSC error AD0001: Analyzer 'FluentAssertions.Analyzers.FluentAssertionsAnalyzer' threw an exception of type 'System.IndexOutOfRangeException' with message 'Index was outside the bounds of the array.'.

```
System.IndexOutOfRangeException : Index was outside the bounds of the array.
at FluentAssertions.Analyzers.NunitCodeFixProvider.MethodInvocationMatcher.TryGetNext(IOperation operation)
at FluentAssertions.Analyzers.NunitCodeFixProvider.AssertThatMatcher.Matches(INamedTypeSymbol type,IOperationMatcher[] matchers)
at FluentAssertions.Analyzers.NunitCodeFixProvider.AssertThatMatcher.Matches(INamedTypeSymbol type,IOperationMatcher[] matchers,MethodInvocationMatcher methodMatcher,IArgumentOperation& argument)
at FluentAssertions.Analyzers.NunitCodeFixProvider.AssertThatMatcher.Is(String propertyMatcher,MethodInvocationMatcher methodMatcher,IArgumentOperation& argument)
at FluentAssertions.Analyzers.NunitCodeFixProvider.TryComputeFixForNunitThat(IInvocationOperation invocation,CodeFixContext context,NunitCodeFixContext t)
at FluentAssertions.Analyzers.NunitCodeFixProvider.TryComputeFixCore(IInvocationOperation invocation,CodeFixContext context,NunitCodeFixContext t,Diagnostic diagnostic)
at FluentAssertions.Analyzers.TestingFrameworkCodeFixProvider`1.TryComputeFix(IInvocationOperation invocation,CodeFixContext context,TTestContext t,Diagnostic diagnostic)
at async FluentAssertions.Analyzers.CodeFixProviderBase`1.RegisterCodeFixesAsync[TTestContext]()
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at async Microsoft.CodeAnalysis.CodeFixes.CodeFixService.GetCodeFixesAsync()
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at async Microsoft.CodeAnalysis.Extensions.IExtensionManagerExtensions.PerformFunctionAsync[T]()
```

### Complete minimal example reproducing the issue

```
Newtonsoft.Json.Linq.JObject actual = new ();
actual.ContainsKey("whatever").Should().BeTrue();
```

### Expected behavior:

no exception thrown during analysis or autofix

### Actual behavior:

crash in VS / failed build

### Versions

* Which version of Fluent Assertions Analyzers are you using?
0.34.1

* Which .NET runtime and version are you targeting? E.g. .NET framework 4.6.1 or .NET Core 2.0.
.Net 4.6.1, .Net 6.0, .Net 8.0

### Additional Information

The CLI issue goes away when upgrading the FluentAssertions from 6.12.2 to 7.0.0