Apps: Add safe, non-null, and let assertions as needed

- gradle gives compile-time errors otherwise
Signed-off-by: Aayush Gupta <theimpulson@e.email>

app/src/main/java/foundation/e/apps/application/model/Installer.kt

@@ -141,7 +141,7 @@ class Installer(private val packageName: String,
     private var receiver = object : BroadcastReceiver() {
         override fun onReceive(context: Context, intent: Intent) {
             if (intent.action == Intent.ACTION_PACKAGE_ADDED &&
-                    (intent.data.encodedSchemeSpecificPart == packageName)) {
+                    (intent.data?.encodedSchemeSpecificPart == packageName)) {
                 Log.i(TAG, "Broadcast received")
                 var path = apk.absolutePath.split("Download")
                 //delete all APK file after install

app/src/main/java/foundation/e/apps/updates/UpdatesManager.kt

@@ -35,7 +35,7 @@ class UpdatesManager(applicationContext: Context) {
         automaticUpdateInterval =
                 preferences.getString(
                         applicationContext.getString(R.string.pref_update_interval_key),
-                        applicationContext.getString(R.string.preference_update_interval_default))
+                        applicationContext.getString(R.string.preference_update_interval_default))!!
                         .toInt()
     }
 

app/src/main/java/foundation/e/apps/utils/Common.kt

@@ -92,7 +92,7 @@ object Common {
     }
 
     fun appHasLaunchActivity(context: Context, packageName: String?): Boolean {
-        return (context.packageManager.getLaunchIntentForPackage(packageName) != null)
+        return (packageName?.let { context.packageManager.getLaunchIntentForPackage(it) } != null)
     }
 
     fun getObjectMapper(): ObjectMapper {