update response body type

Author: pilcrowonpaper

src/oauth2/index.ts

@@ -297,7 +297,7 @@ interface TokenErrorResponseBody {
 
 export interface TokenResponseBody {
 	access_token: string;
-	token_type?: string;
+	token_type: string;
 	expires_in?: number;
 	refresh_token?: string;
 	scope?: string;