Fixes for dynamically controlling iOS drawer status (#1356)

* Fix iOS drawer status control

* Prevent MMDrawerController disabling UI interaction when accidentally assigning a nil drawer controller and toggling that drawer

ios/RCCDrawerController/MMDrawerController/MMDrawerController.m

         }
     }
     else {
-        [self setAnimatingDrawer:animated];
         UIViewController * sideDrawerViewController = [self sideDrawerViewControllerForSide:drawerSide];
-        if (self.openSide != drawerSide) {
-            [self prepareToPresentDrawer:drawerSide animated:animated];
-        }
-        
+
         if(sideDrawerViewController){
+            [self setAnimatingDrawer:animated];
+            if (self.openSide != drawerSide) {
+                [self prepareToPresentDrawer:drawerSide animated:animated];
+            }
+            
             CGRect newFrame;
             CGRect oldFrame = self.centerContainerView.frame;
             if(drawerSide == MMDrawerSideLeft){

ios/RCCDrawerController/RCCDrawerController.m

     UIViewController *centerViewController = [RCCViewController controllerWithLayout:children[0] globalProps:globalProps bridge:bridge];
     
     // left
-    UIViewController *leftViewController = nil;
     NSString *componentLeft = props[@"componentLeft"];
     NSDictionary *passPropsLeft = props[@"passPropsLeft"];
     if (componentLeft) leftViewController = [[RCCViewController alloc] initWithComponent:componentLeft passProps:passPropsLeft navigatorStyle:nil globalProps:globalProps bridge:bridge];
     
     // right
-    UIViewController *rightViewController = nil;
     NSString *componentRight = props[@"componentRight"];
     NSDictionary *passPropsRight = props[@"passPropsRight"];
     if (componentRight) rightViewController = [[RCCViewController alloc] initWithComponent:componentRight passProps:passPropsRight navigatorStyle:nil globalProps:globalProps bridge:bridge];
     {
         bool enabled = [actionParams[@"enabled"] boolValue];
         if ([actionParams[@"side"] isEqualToString:@"left"]) {
-            [super setLeftDrawerViewController: enabled ? rightViewController : nil];
+            [super setLeftDrawerViewController: enabled ? leftViewController : nil];
         } else if ([actionParams[@"side"] isEqualToString:@"right"]) {
             [super setRightDrawerViewController: enabled ? rightViewController : nil];
         }