fix(capacitor-ios): use typed locals in rejectCall for SPM binary compat

Bare nil literals have no contextual type in SPM precompiled context.
Use typed local variables so the compiler can resolve the
CAPPluginCallError initializer and errorHandler call.

Author: j3k0

capacitor/ios/Sources/PurchasePlugin/PurchasePlugin.swift

@@ -377,9 +377,14 @@ public class PurchasePlugin: CAPPlugin, CAPBridgedPlugin {
     }
 
     /// Wrapper for call.reject that works with both CocoaPods (source) and SPM (precompiled xcframework).
-    /// The xcframework doesn't export Swift extension methods like reject(), so we call errorHandler directly.
+    /// The xcframework doesn't export Swift extension methods or initializers with bare nil args,
+    /// so we use typed locals to give the compiler enough context.
     private func rejectCall(_ call: CAPPluginCall, _ message: String) {
-        call.errorHandler(CAPPluginCallError(message: message, code: nil, error: nil, data: [:]))
+        let code: String? = nil
+        let err: Error? = nil
+        let data: [String: Any] = [:]
+        let error = CAPPluginCallError(message: message, code: code, error: err, data: data)
+        call.errorHandler(error)
     }
 
     private func debugLog(_ msg: String) {