[Bug] V compiler not detecting type error for os.read_file "?string" type.

[aqilc]

V version:

> v -v
V 0.1.29 35cbca9

OS: Windows 10 2004

What did you do?

// ./hello.v:

import os

fn main() {
    print("./rand: " + os.read_file("./rand"))
}

> v run "d:\projects\v\hello\hello.v"

What did you expect to see?

An error indicating that I was adding incompatible types(string and ?string).

What did you see instead?

==================
C:\Users\aqilc\AppData\Local\Temp\v\hello.tmp.c: In function 'main__main':
C:\Users\aqilc\AppData\Local\Temp\v\hello.tmp.c:10041:49: error: expected expression before 'Option_string'
  print(string_add(tos_lit("hewwo, heres rand"), Option_string _t191 = os__read_file(tos_lit("./rand"));
                                                 ^~~~~~~~~~~~~
C:\Users\aqilc\AppData\Local\Temp\v\hello.tmp.c: In function '_vinit':
C:\Users\aqilc\AppData\Local\Temp\v\hello.tmp.c:10070:38: warning: integer constant is so large that it is unsigned
  _const_math__bits__max_u64 = ((u64)(18446744073709551615));
                                      ^~~~~~~~~~~~~~~~~~~~
C:\Users\aqilc\AppData\Local\Temp\v\hello.tmp.c:10097:409: warning: integer constant is so large that it is unsigned
   ((u64)(1)), ((u64)(10)), ((u64)(100)), ((u64)(1000)), ((u64)(10000)), ((u64)(100000)), ((u64)(1000000)), ((u64)(10000000)), ((u64)(100000000)), ((u64)(1000000000)), ((u64)(10000000000)), ((u64)(100000000000)), ((u64)(1000000000000)), ((u64)(10000000000000)), ((u64)(100000000000000)), ((u64)(1000000000000000)), ((u64)(10000000000000000)), ((u64)(100000000000000000)), ((u64)(1000000000000000000)), ((u64)(10000000000000000000))}));
                                                                                                                                                                                                                                                                                                                                                                                                                         ^~~~~~~~~~~~~~~~~~~~
C:\Users\aqilc\AppData\Local\Temp\v\hello.tmp.c: In function 'wmain':
...
==================
(Use `v -cg` to print the entire error message)

builder error: 
==================
C error. This should never happen.

[ntrel]

It successfully compile.

read_file returns an optional string. Concatenation won't work with an optional. V should print an error instead of C.

[aqilc]

Yes, it was my naive first test xd
V not printing the error itself is the issue that I wanted to bring attention to, and I realize I should have put that there.