From source code :
// TOA error. Negative for early, positive for late.
// indexing relationships
// maxIndex - actual t0 of the received signal channel estimate
// center - expected t0 of the received signal channel estimate
// toaError - the offset of the channel estimate from its expected position, negative for early
// TOA error should not exceed +/-2 for a normal burst.
// It indicates a failure of the closed loop timing control.
are you using a vm? i had the same error when using a vm