Error while extraction, a .zip, .7zip file in version 1.2.8-r4395 beta

### Configuration
- Keka version: 1.2.8-r4395 beta
- macOS version: 11.1 (20C69)

### Screenshots

### Log
OS: Version 11.1 (Build 20C69)
Keka: v1.2.8-r4395 (WEB) (Sandboxed) (en-GB)
Format detected: Unknown
Binary used: keka7z
Arguments: (
x,
"/Users/elena_chashko/Desktop/Frame Diagram.pdf",
"-o/Users/elena_chashko/Desktop/Frame Diagram.kextraction/Operation",
"-aou",
"-xr!__MACOSX"
)

7-Zip [64] 16.02 : Copyright (c) 1999-2016 Igor Pavlov : 2016-05-21
p7zip Version 16.02 (locale=utf8,Utf16=on,HugeFiles=on,64 bits,4 CPUs x64)
Modified by aONe for Keka

Scanning the drive for archives:
0M Scan /Users/elena_chashko/Desktop/

1 file, 11939884 bytes (12 MiB)

Extracting archive: /Users/elena_chashko/Desktop/Frame Diagram.pdf
70% Open
ERROR:

/Users/elena_chashko/Desktop/Frame Diagram.pdf
Can not open the file as archive

70%

Can't open as archive: 1
Files: 0
Size: 0
Compressed: 0

Error code 2

### Screen Recording

https://user-images.githubusercontent.com/62497891/104605889-5b728800-567f-11eb-999e-3fabe5b146c6.mov