Improve optional checking in native selector

app/NativeMacReceiverSelector/InitDataProvider.swift

@@ -0,0 +1,20 @@
+import Cocoa
+
+class InitDataProvider {
+    static let shared = InitDataProvider()
+
+    let data: InitData
+    
+    private init() {
+        if CommandLine.argc < 2 {
+            fatalError("Missing init data")
+        }
+
+        if let input = CommandLine.arguments[1].data(using: .utf8)
+         , let parsed = try? JSONDecoder().decode(InitData.self, from: input) {
+            self.data = parsed
+        } else {
+            fatalError("Failed to convert and parse init data")
+        }
+    }
+}