Fixed an issue to Not to check Updates or import Fields while the Drupal site MAINTENANCE_MODE is in Install or Update, which generates issues of RuntimeException: Recursive router rebuild detected.

Problem/Motivation

Given that we do have "Drupal" version "^8.4" files ready to install
And we added "google_analytics_reports" module in our ".info.yml" to be enabled at the install step
And we do have some Default content nodes, blocks ..
Then we will face this error report at the install and if the cron job runs in the update process

RuntimeException: Recursive router rebuild detected. in Drupal\Core\Routing\RouteBuilder->rebuild() (line 121 of /var/www/html/test/drupal8403/core/lib/Drupal/Core/Routing/RouteBuilder.php).

Proposed resolution

Not to check Updates or import Fields while the Drupal site MAINTENANCE_MODE != 'install' and MAINTENANCE_MODE != 'update'

I do think as some Drupal core and contrib modules do a check for MAINTENANCE_MODE != 'install' and MAINTENANCE_MODE != 'update' before working on any tasks or events.

 if (defined('MAINTENANCE_MODE') && MAINTENANCE_MODE != 'install' &&  MAINTENANCE_MODE != 'update') {

 }

Remaining tasks

User interface changes

API changes

Check for MAINTENANCE_MODE != 'install' and MAINTENANCE_MODE != 'update' before working on any tasks or events.

Data model changes