feat: provide a helpful error message if no DB access

If unable to access the database provide a helpful error message.

Now the error message will say:
  Unable to connect to the database.

  Ask the website administrator to verify that the database has been
  created/initialized.

  They should also verify that the config/config.php database
  configuration is correct.

Previously it said:
  Unknown Error

Author: JohnVillalovos

lang/en_us.php

@@ -94,6 +94,7 @@ protected function _LoadStrings()
         $strings['Error'] = 'Error';
         $strings['ReturnToPreviousPage'] = 'Return to the last page that you were on';
         $strings['UnknownError'] = 'Unknown Error';
+        $strings['DatabaseConnectionError'] = 'Unable to connect to the database.<br/>Ask the website administrator to verify that the database has been created/initialized.<br/>They should also verify that the <code>config/config.php</code> database configuration is correct.';
         $strings['InsufficientPermissionsError'] = 'You do not have permission to access this resource';
         $strings['MissingReservationResourceError'] = 'A resource was not selected';
         $strings['MissingReservationScheduleError'] = 'A schedule was not selected';

lib/Common/ErrorMessages.php

@@ -8,6 +8,7 @@ class ErrorMessages
     public const MISSING_SCHEDULE = 3;
     public const RESERVATION_NOT_FOUND = 4;
     public const RESERVATION_NOT_AVAILABLE = 5;
+    public const DATABASE_CONNECTION = 6;
 
     private $_resourceKeys = [];
     private static $_instance;
@@ -19,6 +20,7 @@ private function __construct()
         $this->SetKey(ErrorMessages::MISSING_SCHEDULE, 'MissingReservationScheduleError');
         $this->SetKey(ErrorMessages::RESERVATION_NOT_FOUND, 'ReservationNotFoundError');
         $this->SetKey(ErrorMessages::RESERVATION_NOT_AVAILABLE, 'ReservationNotAvailable');
+        $this->SetKey(ErrorMessages::DATABASE_CONNECTION, 'DatabaseConnectionError');
     }
 
     /**

lib/Common/Logging/ExceptionHandler.php

@@ -42,7 +42,15 @@ public function HandleException($exception)
         ob_start();
         debug_print_backtrace();
         error_log(ob_get_clean());
-        call_user_func($this->callback);
+        $errorMessageId = ErrorMessages::UNKNOWN_ERROR;
+        if (
+            str_contains($exception->getMessage(), 'Error connecting to database')
+            || str_contains($exception->getMessage(), 'Error selecting database')
+        ) {
+            $errorMessageId = ErrorMessages::DATABASE_CONNECTION;
+        }
+
+        call_user_func($this->callback, $errorMessageId);
     }
 }