message: Fixes Return type of SignatureHelp is incompatible with the protocol
diff: @@ -969,14 +969,16 @@ export interface SignatureHelp {
  signatures: SignatureInformation[];
  /**
  - * The active signature.
  + * The active signature. Set to `null` if no
  + * signatures exist.
  */
  - activeSignature: number;
  + activeSignature: number | null;
  /**
  - * The active parameter of the active signature.
  + * The active parameter of the active signature. Set to `null`
  + * if the active signature has no parameters.
  */
  - activeParameter: number;
  + activeParameter: number | null;
  }
  /**
  