ah I think that the tvOS one is an actual error

Sources/BuildTool/BuildTool.swift

@@ -61,6 +61,7 @@ struct SimctlOutput: Codable {
 
 enum Error: Swift.Error {
     case terminatedWithExitCode(Int32)
+    case simulatorLookupFailed(message: String)
 }
 
 // TODO: Is there a better way to make sure that this script has access to macOS APIs that are more recent than the package’s deployment target?
@@ -106,12 +107,13 @@ struct BuildTool: ParsableCommand {
 
         let runtimeIdentifier = "com.apple.CoreSimulator.SimRuntime.\(destinationPredicate.runtime)"
         let deviceTypeIdentifier = "com.apple.CoreSimulator.SimDeviceType.\(destinationPredicate.deviceType)"
+
         guard let matchingDevices = simctlOutput.devices[runtimeIdentifier]?.filter({ $0.deviceTypeIdentifier == deviceTypeIdentifier }) else {
-            fatalError("Couldn’t find a simulator with runtime \(runtimeIdentifier) and device type \(deviceTypeIdentifier); available devices are \(simctlOutput.devices)")
+            throw Error.simulatorLookupFailed(message: "Couldn’t find a simulator with runtime \(runtimeIdentifier) and device type \(deviceTypeIdentifier); available devices are \(simctlOutput.devices)")
         }
 
         if matchingDevices.count > 1 {
-            fatalError("Found multiple simulators with runtime \(runtimeIdentifier) and device type \(deviceTypeIdentifier); matching devices are \(matchingDevices)")
+            throw Error.simulatorLookupFailed(message: "Found multiple simulators with runtime \(runtimeIdentifier) and device type \(deviceTypeIdentifier); matching devices are \(matchingDevices)")
         }
 
         return matchingDevices[0].udid