[2.x] [messages] fix: refresh DialogMessage after create to resolve number Expression

[imorland]

Problem

Every time a user sends a private message, the following error is logged:

ErrorException: Object of class Illuminate\Database\Query\Expression could not be converted to int
in vendor/illuminate/database/Eloquent/Concerns/HasAttributes.php

Root Cause

DialogMessage::creating() sets $message->number to a raw DB Expression object — a subquery that computes COALESCE(MAX(number), 0) + 1 — which Eloquent embeds directly in the INSERT statement for atomic, race-condition-safe message numbering within a dialog. This mirrors the same pattern used in Post::creating().

The problem is that Post has a corresponding Post::created() Eloquent boot hook that calls $post->refresh() to replace the Expression with the real integer value from the DB. DialogMessage has no such hook.

When the API's Create endpoint serializes the newly-created DialogMessage in the response, $model->number is still the Expression object. Eloquent's integer cast then attempts (int) $expression, which:

• On PHP 8.3: produces a warning (coerced silently to 0, so the response returns "number": 0)
• On production: Sentry's error handler promotes PHP warnings to ErrorException, causing every message send to log an error

Fix

Call $model->refresh() at the top of DialogMessageResource::created(). This re-queries the database on the write PDO connection and replaces the Expression with the actual integer before any further processing or serialization.

Test

Added test_created_message_response_contains_integer_number_not_expression to CreateTest. Before the fix, this test triggers the PHP warning (confirming the bug). After the fix, all 3 tests pass cleanly with no warnings.

Before fix:
  1 test triggered 1 PHP warning:
  Object of class Illuminate\Database\Query\Expression could not be converted to int

After fix:
  OK (3 tests, 14 assertions)