Execution was interrupted, reason: signal SIGABRT. 2D Array with dictionary-swift

Question

var sectionArray:[[String:Any]] = [ ["sectionName":"Time Cards To Approve","sectionData": [["fname":"true detective","date":"may 20"],["fname":"abbas","date":"may 10"]],"expanaded":false], ["sectionName":"Message Log","sectionData":[["movie":"true detective","event":"Bring food","date":"May 19"],["movie":"false detective","event":"no shoot today","date":"may 20"]],"expanaded":false] ]

I want to get the fname when I try below code it shows the error like **error: Execution was interrupted, reason: signal SIGABRT. The process has been left at the point where it was interrupted, use "thread return -x" to return to the state before expression evaluation. **

let ni = sectionArray[0]
let mi = ni["sectionData"] as! [String:String]
let sh = mi["fname"]