Language server crashes on elephant operator

[MikaelMayer]

The following block crashes the language server on verification

module {:options "/functionSyntax:4"} Library {
  // Library
  datatype Option<T> = Some(value: T) | None
  datatype Result<T> = Success(value: T) | Failure(s: string, pos: int) {
    predicate IsFailure() {
      Failure?
    }
    function PropagateFailure<U>(): Result<U>
      requires IsFailure()
    {
      Failure(s, pos)
    }
    function Extract(): T
      requires !IsFailure()
    {
      value
    }
  }
}
module Parser {
  import opened Library

  datatype Parser = Parser(expected: string) | Log(p: Parser, message: string)
  {
    method {:termination false} Parse(s: string, i: nat)
      returns (result: Result<(string, nat)>)
    {
      if Log? {
        var v1 :- p.Parse(s, i); // Removing this line makes the language server not crash anymore.
      }
      
      result := Failure("bam", i);
    }
  }
}

Error thrown:

at System.String.Ctor(Char c, Int32 count)
   at Microsoft.Dafny.RangeToken.get_val() in dafny\Source\Dafny\AST\DafnyAst.cs:line 8814
   at Microsoft.Dafny.TokenWrapper.get_val() in dafny\Source\Dafny\AST\DafnyAst.cs:line 8791
   at Microsoft.Dafny.LanguageServer.Language.BoogieExtensions.GetLspRange(IToken startToken, IToken endToken) in dafny\Source\DafnyLanguageServer\Language\BoogieExtensions.cs:line 28
   at Microsoft.Dafny.LanguageServer.Workspace.VerificationProgressReporter.<ReportAssertionBatchResult>g__AddChildOutcome|14_0(Counterexample counterexample, AssertCmd assertCmd, IToken token, GutterVerificationStatus status, IToken secondaryToken, String assertDisplay, String assertIdentifier, <>c__DisplayClass14_0& , <>c__DisplayClass14_1& ) in dafny\Source\DafnyLanguageServer\Workspace\VerificationProgressReporter.cs:line 373
...