silverstripe-webpack/app/_config/logs.yml

---
Name: webapp-dev-errors
Only:
  environment: dev
---
SilverStripe\Core\Injector\Injector:
  Psr\Log\LoggerInterface.errorhandler:
    calls:
      pushMyDisplayErrorHandler: [pushHandler, ['%$DisplayErrorHandler']]
  DisplayErrorHandler:
    class: SilverStripe\Logging\HTTPOutputHandler
    constructor:
      - 'notice'
    properties:
      Formatter: '%$SilverStripe\Logging\DetailedErrorFormatter'
      CLIFormatter: '%$SilverStripe\Logging\DetailedErrorFormatter'
---
Name: webapp-live-errors
Except:
  environment: dev
---
SilverStripe\Core\Injector\Injector:
  # Default logger implementation for general purpose use
  Psr\Log\LoggerInterface:
    calls:
      # Save system logs to file
      pushFileLogHandler: [pushHandler, ['%$LogFileHandler']]

  # Core error handler for system use
  Psr\Log\LoggerInterface.errorhandler:
    calls:
      # Save errors to file
      pushFileLogHandler: [pushHandler, ['%$LogFileHandler']]
      # Format and display errors in the browser/CLI
      pushMyDisplayErrorHandler: [pushHandler, ['%$DisplayErrorHandler']]

  # Custom handler to log to a file
  LogFileHandler:
    class: Monolog\Handler\StreamHandler
    constructor:
      - '../silverstripe.log'
      - 'notice'
    properties:
      Formatter: '%$Monolog\Formatter\HtmlFormatter'
      ContentType: text/html

  # Handler for displaying errors in the browser or CLI
  DisplayErrorHandler:
    class: SilverStripe\Logging\HTTPOutputHandler
    constructor:
      - 'error'
    properties:
      Formatter: '%$SilverStripe\Logging\DebugViewFriendlyErrorFormatter'

  # Configuration for the "friendly" error formatter
  SilverStripe\Logging\DebugViewFriendlyErrorFormatter:
    class: SilverStripe\Logging\DebugViewFriendlyErrorFormatter
    properties:
      Title: 'There has been an error'
      Body: 'The website server has not been able to respond to your request'