regex doesn't work

[PaulPuschmann]

I tried to start my first analysis....
panic: runtime error: index out of range [0] with length 0

I found the problem in extparser.go

in function parseFileLine() is a regex query

my variables look like this:
line: 2 drwxr-xr-x root root 1024 6-May-2020 18:31 .
e.fileinfoReg: ^\s*(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+-\w+-\d+)\s+(\d+:\d+)\s+([\S ]+)

Command: res := e.fileinfoReg.FindAllStringSubmatch(line, -1)
Result of the command: res = []

The next step is to try to access res:
size, _ := strconv.Atoi(res[0][5])
This query throws the error that you see in the main program

The question is: what is the goal of the regex query and how can I modify it to make it work?