Please help me to resolved this error "Cannot read property 'toLowerCase' of undefined

An unknown server-side error occurred while processing the command. Original error: Unable to launch WebDriverAgent because of xcodebuild failure: Command ‘Scripts/ -d’ exited with code 1

platformName text iOS
deviceName text iPhone 8
noReset boolean true
platformVersion text 12.0
app text /Users/robertabella/Library/Developer/Xcode/DerivedData/UICatalog-glhanpntglwyeiahfonfatjcafjr/Build/Products/Debug-iphonesimulator/