Code can never be reached because of a logical contradiction

Defect 114074 (STATIC_C)
Checker DEADCODE (subcategory none)
File: /test/csuite/incr_backup/main.c
Function check_table
/test/csuite/incr_backup/main.c, line: 637
Assigning: "op_type" = "(OPERATION_TYPE)(total_changes % 40000UL) / 10000U".

        op_type = (OPERATION_TYPE)(total_changes % CHANGES_PER_CYCLE) / KEYS_PER_TABLE;

/test/csuite/incr_backup/main.c, line: 641
When switching on "op_type", the value of "op_type" must be between 0 and 3.

        switch (op_type) {

/test/csuite/incr_backup/main.c, line: 652
The "switch" governing value "op_type" cannot be "_OPERATION_TYPE_COUNT".

        case _OPERATION_TYPE_COUNT:

/test/csuite/incr_backup/main.c, line: 652
Execution cannot reach this statement: "case _OPERATION_TYPE_COUNT:".

        case _OPERATION_TYPE_COUNT: