Fall back for multi-cam unsupported devices

Author: hiroshihorie

Sources/LiveKit/Track/Capturers/CameraCapturer.swift

@@ -90,12 +90,17 @@ public class CameraCapturer: VideoCapturer {
     private lazy var adapter: VideoCapturerDelegateAdapter = .init(cameraCapturer: self)
 
     #if os(iOS)
+    // static let is lazy by default and AVCaptureMultiCamSession will only be initialized if used.
     private static let _multiCamSession = AVCaptureMultiCamSession()
     #endif
 
     public var captureSession: AVCaptureSession {
         #if os(iOS)
-        Self._multiCamSession
+        if AVCaptureMultiCamSession.isMultiCamSupported {
+            Self._multiCamSession
+        } else {
+            AVCaptureSession()
+        }
         #else
         AVCaptureSession()
         #endif