optional assert in case the provider doesn't return id_token as string

tools/auth/oidc.go

@@ -131,9 +131,9 @@ func (p *OIDC) FetchRawUserInfo(token *oauth2.Token) ([]byte, error) {
 }
 
 func (p *OIDC) parseIdToken(token *oauth2.Token) (jwt.MapClaims, error) {
-	idToken := token.Extra("id_token").(string)
+	idToken, _ := token.Extra("id_token").(string)
 	if idToken == "" {
-		return nil, errors.New("empty id_token")
+		return nil, errors.New("empty or invalid id_token")
 	}
 
 	claims := jwt.MapClaims{}