Lost storage space when bootcamp partition was removed using Bootcamp Assistant

Hello,

I want to recover my storage space that was lost during the removal of bootcamp partition using Bootcamp Assistant.

During the process an error occured which unfortunately, I didn't get a chance to write down what error it was.

Then I checked Disk Utility and my drive looks likes these:

As you can see, my storage capacity was supposed to be 500gb but some 128~129gb is missing.

When I typed diskutil list on terminal, it said this:

I can't seem to find where the former bootcamp partition is even in the diskutil list.

I hope someone could help me on how to fix my problem.

Thank you,

Leo