Need Help with IF Formula in Calculated Column

Hi everyone!

I am hoping you can please help me.  I am calculating a burn rate in a SharePoint List in a calculated column (titled Burn).  I am trying to return a blank value in the Burn column if the Funding Remaining column is blank or if there is an error in the column titled Burn.  Below is a brief description of the columns I am using.

Funding Remaining

Jun Invoice

Jul Invoice

Aug Invoice

The below formula works fine if the funding remaining column is blank, but I have tried to get rid of the errors (predominantly brought on when the trying to average the Jun, Jul, and Aug invoice columns) when they are blank.  

=IF(ISBLANK([Funding Remaining (As of last invoice)]),"",[Funding Remaining (As of last invoice)]/AVERAGE([Aug '23 Invoice (Est.)],[Jul '23 Invoice (Est.)],[Jun '23 Invoice (Est.)]))

Any help you can provide would be appreciated.