Discovered by Luzie on http://board.esxdos.org/viewtopic.php?id=69
Documented by Alcoholics Anonymous on https://github.com/z88dk/z88dk/blob/master/libsrc/_DEVELOPMENT/target/zxn/config/config_esxdos.m4#L101
Reproduced by Xalior for you convenience

1 O.K. ESXDOS
2 Nonsense in ESXDOS
3 Statement END error
4 Wrong file TYPE
5 No such FILE or DIR
6 I/O ERROR
7 Invalid FILENAME
8 Access DENIED
9 Drive FULL
10 Invalid I/O REQUEST
11 No such DRIVE
12 Too many OPEN FILES
13 Bad file DESCRIPTOR
14 No such DEVICE
15 File pointer OVERFLOW
16 Is a DIRECTORY
17 Not a DIRECTORY
18 File already EXISTS
19 Invalid PATH
20 No SYS
21 Path too LONG
22 No such COMMAND
23 File in USE
24 File is READ ONLY
25 Verify FAILED
26 Loading .KO FAILED
27 Directory NOT EMPTY
28 MAPRAM is ACTIVE
29 Drive is BUSY
30 Unknown FILESYSTEM
31 Device is BUSY

Additional error numbers specific to PLOTIT

32 Undefined PLOTIT Error
33 PLOTIT Plugin size Error
34 PLOTIT Plugin header error