Compilation was started.
Area configuration aggregation... 5/9 [===============>------------] 55% 1 min 642.5 MiB In ErrorHandler.php line 61: Warning: Undefined array key "instance" in /var/www/VENDOR/setup/src/Magento/Setup/Module/Di/Compiler/ArgumentsResolver.php on line 171 Try to change the code in /var/www/VENDOR/setup/src/Magento/Setup/Module/Di/Compiler/ArgumentsResolver.php on line 171
Do it like this:
if(isset($this->getInstanceArgument($config['instance'])))
{
$argument = $this->getInstanceArgument($config['instance']);}
Then run setup:di:compile
Do bin/magento c:f and then bin/magento setup:di:compile again
