I am experiencing a similar issue i think. stake_record is a proxy object that contains a list of data. this has worked for years unchanged and just now started throwing this error.
ExternalError: TypeError: ‘get’ on proxy: property ‘0’ is a read-only and non-configurable data property on the proxy target but the proxy did not return its actual value (expected ‘0x0000000000000000000000000000000000000000’ but got ‘[object Object]’)
Maybe you can draw a lesson from the anvil_extras change, then? Is there JavaScript code that creates stake_record that needs adapting? (I’m just trying to be helpful, definitely not fully understanding the situation here, to be clear.)
edit: Maybe it’s related to this Skulpt change? (But note: the Skulpt version being used by Anvil at a given time is not directly discernable from the GitHub repo)
edit2: I moved your post to a new thread to make clear it’s something that’s not yet “Fixed.”