Solution : https://service.sap.com/sap/support/notes/510609 (SAP Service marketplace login required)
Key words : 
system generates abap runtime error message_type_x, reading internal table operation, attached program corrections, person splits reason, program error, splits exist, person level, program saplcxtm, maintenance order, message c7135
Related Notes : 
       
| 547686 | Dump C7135 during scheduling/dispatching in collective order | 
| 510109 | Dump MESSAGE_TYPE_X with message C7135 | 
| 489789 | MESSAGE_TYPE_X with C7135 for relationship with max duration | 
| 453873 |