Why are some BIP numbers missing from BIPs list? If I understood correctly https://github.com/bitcoin/bips contains a list of change proposals that have been accepted as BIPs by the BIP editor?
Why are some of the numbers missing, for example 0155.mediawiki to 0158.mediawiki?
If I understood correctly https://github.com/bitcoin/bips contains a list of change proposals that have been accepted as BIPs by the BIP editor?
  


Correct.


  
  Why are some of the numbers missing, for example 0155.mediawiki to 0158.mediawiki?
  


They haven't been assigned yet. The BIP editor sometimes chooses to reserve a range of number for BIPs around a common theme. When a BIP is proposed matching that theme, it is given a number from the range. Other BIPs get numbers outside of the range.