File.read() always returns 0 bytes in JS backends

[justinas]

Describe the bug

In both js and js_browser backends, File.read() call seems to read 0 bytes

Reproduction Steps

import os

mut buf := []u8{len: 10}
f := os.open('/etc/hosts') or { panic(err) }
n := f.read(mut &buf) or { panic(err) }
println(buf[..n])

Expected Behavior

Using the js backend: expected to either read a non-zero amount of bytes, or raise an error.

Using the js_browser: expected to either fail compilation (since File I/O is unavailable in the browser), or for os.open() to always return an error.

Current Behavior

$ v run read_file.v    # runs as expected
[49, 50, 55, 46, 48, 46, 48, 46, 49, 32]
$  v -o read_file.js read_file.v && node read_file.js
[]
$ v -b js_browser -o read_file.js read_file.v && node read_file.js
[]

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.4.4 ac2dcc2

Environment details (OS name and version, etc.)

NixOS 23.11 (Tapir)
Node v18.18.2

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