You can easily reproduce this error on a Linux machine by adding 
a task at say 8000 days (from year 2004), and then in gantt zoom out
and scroll to 2030's and then dragging the end date handle to try 
and go beyond beyond 2037 or so (about 8600 days - but I'm
assuming this is the 32bit Unix time limit.

It wraps around back to the current project start but also
raises the asserts on a console you will get,
 ** (planner:2728): CRITICAL **: file mrp-project.c: line 1915 
 (mrp_project_calculate_task_work): assertion `finish >= 0' failed

It also renders date bar in gantt in the 2030's not very nicely 
and takes a long time to render this one task (in pango routines ?)

Though these far-in-the-future dates sound silly there are a number 
of things in business which must be stored and planned for with 
long periods of time such as Insurance and maintenance schedules for
buildings e.g. Employers' Liability insurance records in UK must be 
kept for 40 years.