setup error handler to make (undefined array key) fatal

[simonLeary42]

also:

• remove arrayGet function which is now redundant
• display xdebug message in error page when display_errors and html_errors are enabled in PHP config
• explicitly enable all xdebug features in dev environment
• reorder message in error log so that less import information goes near the end
• remove ini_set which never gets run because internalServerError never returns

[Copilot]

Pull request overview

This PR introduces a custom error handler to convert PHP "Undefined array key" warnings into fatal exceptions by throwing ArrayKeyException. This ensures that array access errors are caught early and handled consistently with the existing arrayGet() utility function.

• Added errorHandler() method to convert "Undefined array key" warnings to fatal exceptions
• Enhanced xdebug configuration for better development debugging capabilities
• Added configuration flag to enable/disable the error handler

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
tools/docker-dev/web/Dockerfile	Expanded xdebug modes to include develop, debug, gcstats, profile, and trace for enhanced debugging in development environment
resources/lib/UnityHTTPD.php	Added new errorHandler() method to convert "Undefined array key" warnings to exceptions; added xdebug message display in error output; reordered errorLog method statements
resources/init.php	Registered the new error handler when enabled via configuration
deployment/overrides/phpunit/config/config.ini	Disabled error handler for PHPUnit tests to prevent interference with test execution
defaults/config.ini.default	Added enable_error_handler configuration flag (enabled by default)

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