ORA-02436: date or system variable wrongly specified in CHECK constraint
Try (for the CHECK constraint) ... 

t_type_end_date IS NULL


Also, when using your DDL code in apex.oracle.com (Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production), we get 

ORA-00972: identifier is too long


this is caused by the line

CONSTRAINT unique_t_type_t_type_start_date UNIQUE(t_type,t_type_start_date)