Trying to use JSONata $map for Nested arrays, getting Invalid JSONata expression: Expected "{", got "["

[dubnemo]

Related comment, which I don't understand why it would behave this way.

$filter array is return undefined in logs - flow.fileContents or payload.arrayEntry not accessible?

To note, if theere is only one match the output will be an object not an array with a single object, this maybe OK for you, but if you require an array of object/s then enclose the expression in square brackets to force an array output. [$flowContext("fileContents"), function($v) { $v.farmerEmailAddress = msg.emailAddress } )]