NullPointerException when using AndroidDriver and calling WebDriverWait - appium

Question

My code below tries to wait until our native app loads. But it receives NPE:
RemoteWebDriver driver =
new AndroidDriver<MobileElement>//this gets NPE below
//new RemoteWebDriver //this works!!
(new URL("http://127.0.0.1:4723/wd/hub"), capabilities);
new WebDriverWait(driver, 30).until(
ExpectedConditions.presenceOfElementLocated(
By.xpath("//*[contains(#text, 'Tan')]")));
When I replace AndroidDriver with RemoteDriver, everything works as expected! Our app launches and our test code waits until the app loads. The problem is, we cannot use mobile device specific API using RemoteDriver.
Appium GUI v1.4.16.1 (Ophiuchus). Please tell if any other version info is needed, as I'm not good at npm etc. But I downloaded all of the stuff last week.
Here is the stack trace:
java.lang.NullPointerException
at org.openqa.selenium.remote.ErrorHandler.throwIfResponseFailed(ErrorHandler.java:152)
at org.openqa.selenium.remote.RemoteWebDriver.execute(RemoteWebDriver.java:636)
at io.appium.java_client.DefaultGenericMobileDriver.execute(DefaultGenericMobileDriver.java:40)
at io.appium.java_client.AppiumDriver.execute(AppiumDriver.java:1)
at io.appium.java_client.android.AndroidDriver.execute(AndroidDriver.java:1)
at org.openqa.selenium.remote.RemoteWebDriver.findElement(RemoteWebDriver.java:369)
at io.appium.java_client.DefaultGenericMobileDriver.findElement(DefaultGenericMobileDriver.java:56)
at io.appium.java_client.AppiumDriver.findElement(AppiumDriver.java:1)
at io.appium.java_client.android.AndroidDriver.findElement(AndroidDriver.java:1)
at org.openqa.selenium.remote.RemoteWebDriver.findElementByXPath(RemoteWebDriver.java:474)
at io.appium.java_client.DefaultGenericMobileDriver.findElementByXPath(DefaultGenericMobileDriver.java:134)
at io.appium.java_client.AppiumDriver.findElementByXPath(AppiumDriver.java:1)
at io.appium.java_client.android.AndroidDriver.findElementByXPath(AndroidDriver.java:1)
at org.openqa.selenium.By$ByXPath.findElement(By.java:361)
at org.openqa.selenium.remote.RemoteWebDriver.findElement(RemoteWebDriver.java:361)
at io.appium.java_client.DefaultGenericMobileDriver.findElement(DefaultGenericMobileDriver.java:52)
at io.appium.java_client.AppiumDriver.findElement(AppiumDriver.java:1)
at io.appium.java_client.android.AndroidDriver.findElement(AndroidDriver.java:1)
at org.openqa.selenium.support.ui.ExpectedConditions.findElement(ExpectedConditions.java:895)
at org.openqa.selenium.support.ui.ExpectedConditions.access$000(ExpectedConditions.java:41)
at org.openqa.selenium.support.ui.ExpectedConditions$6.apply(ExpectedConditions.java:181)
at org.openqa.selenium.support.ui.ExpectedConditions$6.apply(ExpectedConditions.java:178)
at org.openqa.selenium.support.ui.FluentWait.until(FluentWait.java:238)
Here is what I see on Appium GUI:
> info: [debug] Appium session started with sessionId 4153c447-cfba-45db-a23a-1e603a3e0e7c
> info: <-- POST /wd/hub/session 303 17598.310 ms - 74
> info: --> GET /wd/hub/session/4153c447-cfba-45db-a23a-1e603a3e0e7c {}
> info: [debug] Responding to client with success: {"status":0,"value":{"platform":"LINUX","browserName":"Android","platformVersion":"4.4.2","webStorageEnabled":false,"takesScreenshot":true,"javascriptEnabled":true,"databaseEnabled":false,"networkConnectionEnabled":true,"locationContextEnabled":false,"warnings":{},"desired":{"app":"C:\\Temp\\appium\\akbank-release.apk","appActivity":"com.akbank.akbankdirekt.ui.prelogin.SplashActivity","platformName":"Android","deviceName":"OJOBUCIBGEKNTKYS"},"app":"C:\\Temp\\appium\\akbank-release.apk","appActivity":"com.akbank.akbankdirekt.ui.prelogin.SplashActivity","platformName":"Android","deviceName":"OJOBUCIBGEKNTKYS"},"sessionId":"4153c447-cfba-45db-a23a-1e603a3e0e7c"}
> info: <-- GET /wd/hub/session/4153c447-cfba-45db-a23a-1e603a3e0e7c 200 4.362 ms - 667 {"status":0,"value":{"platform":"LINUX","browserName":"Android","platformVersion":"4.4.2","webStorageEnabled":false,"takesScreenshot":true,"javascriptEnabled":true,"databaseEnabled":false,"networkConnectionEnabled":true,"locationContextEnabled":false,"warnings":{},"desired":{"app":"C:\\Temp\\appium\\akbank-release.apk","appActivity":"com.akbank.akbankdirekt.ui.prelogin.SplashActivity","platformName":"Android","deviceName":"OJOBUCIBGEKNTKYS"},"app":"C:\\Temp\\appium\\akbank-release.apk","appActivity":"com.akbank.akbankdirekt.ui.prelogin.SplashActivity","platformName":"Android","deviceName":"OJOBUCIBGEKNTKYS"},"sessionId":"4153c447-cfba-45db-a23a-1e603a3e0e7c"}
> info: --> POST /wd/hub/session/4153c447-cfba-45db-a23a-1e603a3e0e7c/element {"using":"xpath","value":"//*[contains(#text, 'Tan')]"}
> info: [debug] Waiting up to 0ms for condition
> info: [debug] Pushing command to appium work queue: ["find",{"strategy":"xpath","selector":"//*[contains(#text, 'Tan')]","context":"","multiple":false}]
> info: [debug] [BOOTSTRAP] [debug] Got data from client: {"cmd":"action","action":"find","params":{"strategy":"xpath","selector":"//*[contains(#text, 'Tan')]","context":"","multiple":false}}
> info: [debug] [BOOTSTRAP] [debug] Got command of type ACTION
> info: [debug] [BOOTSTRAP] [debug] Got command action: find
> info: [debug] [BOOTSTRAP] [debug] Finding //*[contains(#text, 'Tan')] using XPATH with the contextId: multiple: false
> info: [debug] [BOOTSTRAP] [debug] Returning result: {"value":"Could not find an element using supplied strategy. ","status":7}
> info: [debug] Condition unmet after 8397ms. Timing out.
> info: [debug] Responding to client with error: {"status":7,"value":{"message":"An element could not be located on the page using the given search parameters.","origValue":"Could not find an element using supplied strategy. "},"sessionId":"4153c447-cfba-45db-a23a-1e603a3e0e7c"}
> info: <-- POST /wd/hub/session/4153c447-cfba-45db-a23a-1e603a3e0e7c/element 500 8402.114 ms - 230

Answer 1

I've put a sleep before wait and now I don't get NPE:
RemoteWebDriver driver =
new AndroidDriver<MobileElement>//this gets NPE below
//new RemoteWebDriver //this works!!
(new URL("http://127.0.0.1:4723/wd/hub"), capabilities);
Thread.sleep(15000);
new WebDriverWait(driver, 30).until(
ExpectedConditions.presenceOfElementLocated(
By.xpath("//*[contains(#text, 'Tan')]")));
NPE was thrown as soon as the app was first loaded. I think this is an internal Appium problem.