[7.x] Catch and report exceptions thrown during schedule run execution

[michaeldyrynda]

As the task scheduler executes scheduled events sequentially, if any of the tasks were to raise a Throwable, any subsequent tasks in that execution thread will not be processed.

Consider the following task schedule:

$schedule->call(function () {
    // Some task logic
}}->everyMinute();

$schedule->call(function () {
    throw new Exception('Some task that throws an exception');
})->everyMinute();

$schedule->call(function () {
    // Some task that is never run
})->everyMinute();

Whilst your error reporting tool or logging channel would likely report this occurrence, none of the tasks subsequent to the Throwable would be run at all, which is undesirable.

In order to allow task execution to continue to flow, whilst also reporting the exception to your error reporting tool or logging channel, catching and reporting the Throwable will be sufficient to allow the remaining tasks to execute.

I've also moved the dispatch of the ScheduledTaskFinished event and setting of eventsRan inside the try block, as a Throwable being raised indicates that the task did not finish running, and as such should not be flagged as having been run.