[PATCH] erofs-utils: fix resource leaks and missing returns on error paths

[Nithurshen]

Hi Xiang,

Both the patches LGTM.

I tested the missing return by truncating an image to force an I/O 
error, and the FUSE daemon now correctly aborts instead of hanging. 
I also dynamically tested the memory leak fix using Valgrind with a 
10MB file and an injected Z_STREAM_ERROR, confirming 0 bytes lost.

The only note is that this should be sent as 2 separate patches in 
the same thread.

Reviewed-by: Nithurshen <nithurshen.dev at gmail.com>
Tested-by: Nithurshen <nithurshen.dev at gmail.com>