Hotfix for v3.6.1 - Avoid possible NullPointerException

Avoid possible NullPointerException setting toolbar subtitle at
`FileExplorerActivityLollipop`

Author: javiergm1983

app/build.gradle

@@ -8,8 +8,8 @@ android {
         applicationId "mega.privacy.android.app"
         minSdkVersion 21
         targetSdkVersion 27
-        versionCode 234
-        versionName "3.6.1 (234)"
+        versionCode 238
+        versionName "3.6.1 (238)"
         multiDexEnabled true
     }
 

app/src/main/AndroidManifest.xml

@@ -2,8 +2,8 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="mega.privacy.android.app"
     android:installLocation="internalOnly"
-    android:versionCode="234"
-    android:versionName="3.6.1 (234)">
+    android:versionCode="238"
+    android:versionName="3.6.1 (238)">
 
     <uses-feature android:name="android.hardware.camera.autofocus" android:required="false" />
     <uses-feature android:name="android.hardware.camera" android:required="false"/>

app/src/main/java/mega/privacy/android/app/MegaApplication.java

@@ -98,7 +98,7 @@
 public class MegaApplication extends MultiDexApplication implements MegaGlobalListenerInterface, MegaChatRequestListenerInterface, MegaChatNotificationListenerInterface, MegaChatCallListenerInterface, NetworkStateReceiver.NetworkStateReceiverListener, MegaChatListenerInterface {
 	final String TAG = "MegaApplication";
 
-	static final public String USER_AGENT = "MEGAAndroid/3.6.1_234";
+	static final public String USER_AGENT = "MEGAAndroid/3.6.1_238";
 
 	DatabaseHandler dbH;
 	MegaApiAndroid megaApi;

app/src/main/java/mega/privacy/android/app/lollipop/FileExplorerActivityLollipop.java

@@ -2600,7 +2600,9 @@ public void onContactRequestsUpdate(MegaApiJava api,
 	}
 
 	public void setToolbarSubtitle(String s) {
-		aB.setSubtitle(s);
+	    if (aB != null) {
+            aB.setSubtitle(s);
+        }
 	}
 
 	@Override

app/src/main/res/values/strings_donottranslate.xml

@@ -2,7 +2,7 @@
 <resources>
     <string name="app_name" context="Name of the app" translatable="false">MEGA</string>
     <string name="pdf_app_name" context="PDF viewer app name" translatable="false">MEGA PDF Viewer</string>
-    <string name="app_version" context="Version number of the app" translatable="false">3.6.1 (234)</string>
+    <string name="app_version" context="Version number of the app" translatable="false">3.6.1 (238)</string>
     <string name="sdk_version" context="SDK version" translatable="false">a69204a</string>
     <string name="karere_version" context="MEGAchat SDK version" translatable="false">9938c91</string>
     <string name="prolite_account" context="PRO Lite account" translatable="false">Lite</string>