Overflowed constant

The overflowed value due to arithmetic on constants is too small or unexpectedly negative, causing incorrect computations. Integer overflow occurs in arithmetic on constant operands
/src/mongo/db/storage/key_string.cpp:1436: INTEGER_OVERFLOW 140918 "bytesNeeded" = "(64 - mongo::countLeadingZeros64(value) + 7) / 8", its value is now 0.
/src/mongo/db/storage/key_string.cpp:1443: INTEGER_OVERFLOW 140918 Expression "bytesNeeded - 1UL", which is equal to 18446744073709551615, where "bytesNeeded" is known to be equal to 0, underflows the type that receives it, an unsigned integer 64 bits wide.