BaseSetupWizardActivity: Handle NPE when WiFi service is unavailable

Do not let SetupWizard crash in case the WiFi service is not available,
which can happen in case of devkits without built-in WiFi support.

Change-Id: Iba72e941b5e4995e865c70cb6c2b6be9a721addc

src/org/lineageos/setupwizard/BaseSetupWizardActivity.java

@@ -301,7 +301,7 @@ public abstract class BaseSetupWizardActivity extends AppCompatActivity implemen
 
     protected final boolean tryEnablingWifi() {
         WifiManager wifiManager = getSystemService(WifiManager.class);
-        return wifiManager.setWifiEnabled(true);
+        return wifiManager != null && wifiManager.setWifiEnabled(true);
     }
 
     private boolean isFirstRun() {