[BUG] Statistics generator throws a warning in Docker environment

[mdziekon]

Problem description

When working in Docker environment (introduced in #251), the statistics calculation script (admin/autostatbuilder.php) throws a warning related to cache file being inaccessible for write:

 Warning: file_put_contents(../cache/data/last_stats_update.php): failed to open stream: No such file or directory in /var/www/html/admin/autostatbuilder.php on line 1029

The probles does not seem to be fatal, however it most likely affect the Signature generation script (currently broken in Docker environment, see #253).

Engine details

• Engine version:
  • version X.Y.Z
  • commit 77f8090
• Custom modifications:
  • Yes
  • No
• Environment:
  • local
  • testing (inaccessible from the outside)
  • production (accessible from the outside world)
• Configuration:
  • Game speeds: N/A
  • Debris settings: N/A
  • Any other relevant config entry: N/A

Steps to reproduce

Prerequisites:

• Random user X exists
• Logged in as Administrator

Steps to reproduce the behavior:

1. Go to Admin panel
2. Calculate statistics (use Recalculate Statistics function)

Expected behavior

• Statistics are calculated
• No errors and warnings are being displayed

Actual behavior

• Statistics are calculated
• A warnings is thrown

Reproduction environment

Game server environment:

• Docker (as described in https://github.com/mdziekon/UniEngine#docker)