In order to fix this issue, you need to compare your save/load scripts and make sure they're writing/reading the same number of times. Make sure one doesn't cut short (Error Reading Byte means that you've already reached the end of the file, but you're still trying to read). Maybe you're reading an empty file? Check to make sure the file exists first.
Maybe the save script skips to a different spot to write the deathtime and you didn't do the same in load? The error mentions the first microtime read - how many reads are done before that? That will give you a clue of where to look in your save script. Maybe the save script stops just before that write in some cases. Maybe your save script isn't saving the 'microtime'. If you don't need that you can just remove the microtime lines from the load script.