关闭/打开LocationSensor后，LocationManager在OnFormShow上崩溃

Question

我使用的是本地位置管理器，但是如果我关闭位置传感器然后再次打开，应用程序会在启动后立即崩溃（位置传感器图标只是闪烁）。但是，如果我嘲笑一个新位置，那么它不会崩溃并且工作正常。

Ps。：同时，当应用程序在启动时不断崩溃，如果我运行Waze，等待10秒，然后再次启动，它就可以运行。

unit Unit1;

interface

uses
  System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants,
  FMX.Types, FMX.Controls, FMX.Forms, FMX.Graphics, FMX.Dialogs,
  Androidapi.JNI.Location, Androidapi.JNIBridge, Androidapi.JNI.JavaTypes,
  Androidapi.JNI.Os, FMX.Layouts, FMX.ListBox, FMX.StdCtrls,
  FMX.Controls.Presentation, Androidapi.Helpers;

type

  TLocationListener = class;

  TForm1 = class(TForm)
    Label1: TLabel;
    procedure FormShow(Sender: TObject);
  private
    FLocationManager : JLocationManager;
    locationListener : TLocationListener;
  public
    destructor Destroy; override;
    procedure onLocationChanged(location: JLocation);
  end;

  TLocationListener = class(TJavaLocal, JLocationListener)
  private
    [weak]
    FParent : TForm1;
  public
    constructor Create(AParent : TForm1);
    procedure onLocationChanged(location: JLocation); cdecl;
    procedure onProviderDisabled(provider: JString); cdecl;
    procedure onProviderEnabled(provider: JString); cdecl;
    procedure onStatusChanged(provider: JString; status: Integer; extras: JBundle); cdecl;
  end;

var
  Form1: TForm1;

implementation

{$R *.fmx}

uses FMX.Helpers.Android, Androidapi.JNI.GraphicsContentViewText;

{ TLocationListener }

constructor TLocationListener.Create(AParent: TForm1);
begin
  inherited Create;
  FParent := AParent;
end;

procedure TLocationListener.onLocationChanged(location: JLocation);
begin
  FParent.onLocationChanged(location);
end;

procedure TLocationListener.onProviderDisabled(provider: JString);
begin

end;

procedure TLocationListener.onProviderEnabled(provider: JString);
begin

end;

procedure TLocationListener.onStatusChanged(provider: JString; status: Integer;
  extras: JBundle);
begin

end;

{ TForm1 }

destructor TForm1.Destroy;
begin
  if Assigned(locationListener) then
    FLocationManager.removeUpdates(locationListener);
  inherited;
end;

procedure TForm1.FormShow(Sender: TObject);
var
  LocationManagerService: JObject;
  location : JLocation;
begin
  if not Assigned(FLocationManager) then
  begin
    LocationManagerService := SharedActivityContext.getSystemService(TJContext.JavaClass.LOCATION_SERVICE);
    FLocationManager := TJLocationManager.Wrap((LocationManagerService as ILocalObject).GetObjectID);
    if not Assigned(locationListener) then
      locationListener := TLocationListener.Create(self);
    FLocationManager.requestLocationUpdates(TJLocationManager.JavaClass.GPS_PROVIDER, 2000, 20, locationListener,TJLooper.JavaClass.getMainLooper);
  end;
  location := FLocationManager.getLastKnownLocation(TJLocationManager.JavaClass.GPS_PROVIDER);
  onLocationChanged(location);
end;

procedure TForm1.onLocationChanged(location: JLocation);
begin
 Label1.Text := FloatToStr((location.getSpeed*3600)/1000) + ' km/h';
end;

end.

我错过了什么？事件的哪个部分可能导致此次崩溃？