save FirebaseInstanceId.getInstance() access.

`FirebaseInstanceId.getInstance()` can throw exceptions. For example if Firebase was not initialized.

android/src/main/java/com/evollu/react/fcm/FIRMessagingModule.java

@@ -70,8 +70,13 @@ public class FIRMessagingModule extends ReactContextBaseJavaModule implements Li
 
     @ReactMethod
     public void getFCMToken(Promise promise) {
+        try {
              Log.d(TAG, "Firebase token: " + FirebaseInstanceId.getInstance().getToken());
              promise.resolve(FirebaseInstanceId.getInstance().getToken());
+        } catch (Throwable e) {
+             e.printStackTrace();
+             promise.reject(null,e.getMessage());
+        }
     }
 
     @ReactMethod