PowerQuery: Getting error info when it's too late to `try`? - powerquery

Question

Short Version
In PowerQuery, when the error occurs before I'm able to use try, how do I catch an error and get the reason and message strings?
Long Version
In PowerQuery (using Excel if that matters),
OleDb.DataSource(
MyConnectionString,
[Query="SELECT * FROM NonExistingTable"]
)
returns an error. Great. I want that because I'm trying to make a quick and dirty tool that grabs data from multiple tables, but some people don't have access to all tables and who knows what else will happen in the future. However, I want to handle that error so it degrades gracefully, preferably presenting an explanation to the user based on the info within the error.
Therefore, I attempted error handling with try, like so:
try OleDb.DataSource(
MyConnectionString,
[Query="SELECT * FROM NonExistingTable"]
)
and I had expected it to return something like
[
HasError = true,
Error = [
Reason = "OLE DB",
Message = "Invalid object name: 'NonExistingTable'.",
Details = ...
]
]
but instead, what's returned is
[
HasError = false,
Value = Error
]
where Error is an error object containing the information I want.
I had then tried to make a workaround with something like
let
tryRecord = try OleDb.DataSource(MyConnectionString, [Query="SELECT * FROM NonExistingTable"]),
ret = if (tryRecord[HasError]) then
// It's an error
tryRecord
else try
// If Value.Type() doesn't throw an error then tryRecord[Value] isn't an error, so return it.
(if Value.Type(tryRecord[Value]) = null then null else tryRecord)
otherwise
// tryRecord[Value] contains an error!
try error tryRecord[Value]
in
ret
but try error tryRecord[Value] is not unpacking the error object within tryRecord[Value] like I had hoped.
How do I get the reason and message strings from an error object?