If frames timestamps are incorrect and are not strictly increasing, using them to perform motion interpolation or extrapolation will lead to wrong behavior, at will create fake huge jumps. In this case, we just ignore Ego-Motion extrapolation (we use the previous pose as init) and Undistortion (no undistortion performed).
Moreover, if Ego-motion step fails or give irrelevant results, the Localization step may fails too. In this case, we should just ignore the result, as it is likely to be wrong. If an error occurs, we ignore this frame and reset to previous frame pose.