I’ve been fiddling with this and I believe I figured out my problem. Sharing here for anyone else who wants to utilize something like this in the future…
The connector works great so props to Oliver on making and providing this solution. the problems I was encountering were environment specific, the error I pasted above was happening in the getMailboxSettings() being made for each account returned in getAllAccounts(), some of the accounts in list were not graphAPI enabled, figuring out what ones exactly was a bit of a difficult task, so I opted to just alter the connector a bit.
what I had to do to get this to work was modify the getAllAccounts() function to add a header and count parameter to enable some of the more complicated query use in MS Graph - see link. I added ConsistencyLevel header so that I could filter the response a little more finely to limit my calls to just our active employee base.
async getAllAccounts(): Promise<Map<string, string>[]> {
let results: Map<string, string>[] = []
let response: PageCollection = await this.client
.api('/users')
.header ('ConsistencyLevel', 'eventual')
.top(100)
.count(true)
.select([
'id',
'userPrincipalName',
'mail',
'displayName',
'givenName',
'surname',
'lastPasswordChangeDateTime',
])
.filter(this.filter)
.get()
but I was still getting errors even after I got the query correct, so what I eventually came up with was just to wrap the getMailboxSettings() in a try-catch block as ultimately i did not care about the random mailboxes that were not api enabled for this purpose, so just ignore them and move on.
async getMailboxSettings(identity: string): Promise<Map<string, string>> {
let result: Map<string, string> = new Map()
try{
await this.client
.api('/users/' + identity + '/mailboxSettings/automaticRepliesSetting')
.top(1)
//.select(['status', 'scheduledStartDateTime', 'scheduledEndDateTime'])
.get()
.then((mailboxSettings) => {
result.set('automaticRepliesSetting', mailboxSettings.status)
result.set('scheduledEndDateTime', mailboxSettings.scheduledEndDateTime.dateTime)
result.set('scheduledStartDateTime', mailboxSettings.scheduledStartDateTime.dateTime)
if (mailboxSettings.status == 'alwaysEnabled') {
result.set('automaticRepliesStatus', 'enabled')
}
if (mailboxSettings.status == 'scheduled') {
const start = new Date(mailboxSettings.scheduledStartDateTime.dateTime)
const end = new Date(mailboxSettings.scheduledEndDateTime.dateTime)
const now = new Date()
if (start < now && end > now) {
result.set('automaticRepliesStatus', 'enabled')
} else {
result.set('automaticRepliesStatus', 'disabled')
}
}
if (mailboxSettings.status == 'disabled') {
result.set('automaticRepliesStatus', 'disabled')
}
})
} catch(error){
console.error('Error fetching mailbox settings:', error)
}
return result
}
repacked, and reuploaded the connector and ran an aggregation and I have the account population i needed, with the data required! next step, workflows to set work reassignment for out of office 
