do not throw when calling stop if already stopped

@@ -208,7 +208,7 @@ class MobileScannerPlugin : FlutterPlugin, ActivityAware, MethodChannel.MethodCa
             handler!!.stop()
             result.success(null)
         } catch (e: AlreadyStopped) {
-            result.error("MobileScanner", "Called stop() while already stopped!", null)
+            result.success(null)
         }
     }
 

@@ -107,11 +107,7 @@ public class SwiftMobileScannerPlugin: NSObject, FlutterPlugin {
     private func stop(_ result: @escaping FlutterResult) {
         do {
             try mobileScanner.stop()
-        } catch {
-            result(FlutterError(code: "MobileScanner",
-                                message: "Called stop() while already stopped!",
-                                details: nil))
-        }
+        } catch {}
         result(nil)
     }
 

@@ -260,9 +260,8 @@ public class MobileScannerPlugin: NSObject, FlutterPlugin, FlutterStreamHandler,
 
     func stop(_ result: FlutterResult) {
         if (device == nil) {
-            result(FlutterError(code: "MobileScanner",
-                                    message: "Called stop() while already stopped!",
-                                    details: nil))
+            result(nil)
+
             return
         }
         captureSession.stopRunning()