Get OAuth Custom Connector to check for valid token before initiating login flow again

I posted separately about getting my Netsuite custom connector to work in Power Query/Power BI and FINALLY got it working, but now I'm running into an issue where every single time I edit a query or refresh, it prompts me to log in again (go to the Netsuite log in form, etc.)

And due to how the API pages, I have almost 30 different queries with unions and joins to get the complete datasets. So basically, every time I "Close & Apply" or "Refresh", I have to login 30+ times for each query.

Below is the code in my .pq file:

[Version = "1.0.0"]
section NetsuiteConnector;

client_id = Text.FromBinary(Extension.Contents("client_id.txt"));
client_secret = Text.FromBinary(Extension.Contents("client_secret.txt"));
redirect_uri = "https://localhost";
token_uri = {my_token_uri};
authorize_uri = {my_authorize_uri};
logout_uri = "https://login.microsoftonline.com/logout.srf";
state1="ykv2XLx1BpT5Q0F3MRPHb94j";

// Login modal window dimensions
windowWidth = 720;
windowHeight = 1024;


[DataSource.Kind="NetsuiteConnector", Publish= "NetsuiteConnector.Publish"]
shared NetsuiteConnector.Contents = (url as text, query as text) =>
    let 
        headers = [#"Prefer" = "transient"],
        body = Json.FromValue([q = query]),
        source = Json.Document(Web.Contents(url,[Headers = headers, Content = body]))
    in
        source; 

// Data Source Kind description
NetsuiteConnector= [
    TestConnection = (dataSourcePath) => { "NetsuiteConnector.Contents", dataSourcePath },
    Authentication = [
        OAuth = [
            StartLogin=StartLogin,
            FinishLogin=FinishLogin,
            Refresh=Refresh,
            Logout=Logout
        ]
    ],
    Label = Extension.LoadString("DataSourceLabel")
];

// Data Source UI publishing description
NetsuiteConnector.Publish = [
    Beta = true,
    Category = "Other",
    ButtonText = { Extension.LoadString("ButtonTitle"), Extension.LoadString("ButtonHelp") },
    LearnMoreUrl = "https://powerbi.microsoft.com/",
    SourceImage = NetsuiteConnector.Icons,
    SourceTypeImage = NetsuiteConnector.Icons
];

// Helper functions for OAuth2: StartLogin, FinishLogin, Refresh, Logout
StartLogin = (resourceUrl, state, display) =>
    let
        authorizeUrl = authorize_uri/*& "?" & Uri.BuildQueryString([
            
            redirect_uri = redirect_uri,
            client_id = client_id,
            response_type = "code",           
            state = state1,
            scope = "rest_webservices"
        ])
        */
    in
        [
            LoginUri = authorizeUrl,
            CallbackUri = redirect_uri,
            WindowHeight = 720,
            WindowWidth = 1024,
            Context = null
        ];

FinishLogin = (context, callbackUri, state) =>
    let
        // parse the full callbackUri, and extract the Query string
        parts = Uri.Parts(callbackUri)[Query],
        // if the query string contains an "error" field, raise an error
        // otherwise call TokenMethod to exchange our code for an access_token
        result = if (Record.HasFields(parts, {"error", "error_description"})) then 
                    error Error.Record(parts[error], parts[error_description], parts)
                 else
                    TokenMethod("authorization_code", "code", parts[code])
    in
        result;

Refresh = (resourceUrl, refresh_token) => TokenMethod("refresh_token", "refresh_token", refresh_token);

Logout = (token) => logout_uri;


// Exchange code for access token

TokenMethod = (grantType, tokenField, code) =>
    let
        queryString = [
            grant_type = "authorization_code",
            redirect_uri = redirect_uri,
            client_id = client_id,
            client_secret = client_secret
        ],
        queryWithCode = Record.AddField(queryString, tokenField, code),

        tokenResponse = Web.Contents(token_uri, [
            Content = Text.ToBinary(Uri.BuildQueryString(queryWithCode)),
            Headers = [
                #"Content-type" = "application/x-www-form-urlencoded",
                #"Accept" = "application/json"
            ],
            ManualStatusHandling = {400} 
        ]),
        body = Json.Document(tokenResponse),
        result = if (Record.HasFields(body, {"error", "error_description"})) then 
                    error Error.Record(body[error], body[error_description], body)
                 else
                    body
    in
        result;

Value.IfNull = (a, b) => if a <> null then a else b;

GetScopeString = (scopes as list, optional scopePrefix as text) as text =>
    let
        prefix = Value.IfNull(scopePrefix, ""),
        addPrefix = List.Transform(scopes, each prefix & _),
        asText = Text.Combine(addPrefix, " ")
    in
        asText;
        

NetsuiteConnector.Icons = [
    Icon16 = { Extension.Contents("NetsuiteConnector16.png"), Extension.Contents("NetsuiteConnector20.png"), Extension.Contents("NetsuiteConnector24.png"), Extension.Contents("NetsuiteConnector32.png") },
    Icon32 = { Extension.Contents("NetsuiteConnector32.png"), Extension.Contents("NetsuiteConnector40.png"), Extension.Contents("NetsuiteConnector48.png"), Extension.Contents("NetsuiteConnector64.png") }
];

A sample query looks like this:

let
    result = NetsuiteConnector.Contents("https://{my_netsuite_ site}.suitetalk.api.netsuite.com/services/rest/query/v1/suiteql?limit=1000","SELECT * FROM transaction WHERE recordtype = 'invoice'")
in
    result

The tokens should only expire every hour, which I think is fine if I have to re-authenticate once an hour, but having to re-authenticate 30 times every time I change something in the query won't work. Not to mention I would eventually like to set up scheduled refresh in PBI service, so thinking about how to do that too.

Is there a way to implement in the pq logic of the custom connector a way to check if the current token is valid before initiating the whole OAuth flow again?