Include function name in error messages

[antocuni]

Consider the following:

def foo() -> int:
    return 1 + "hello"

def main() -> None:
    foo()

Currently, we get this error:

❯ spy /tmp/x.spy 
TypeError: cannot do `i32` + `str`
   --> /tmp/x.spy:2:12
  2 |     return 1 + "hello"
    |            ^ this is `i32`

   --> /tmp/x.spy:2:16
  2 |     return 1 + "hello"
    |                |_____| this is `str`

   --> /tmp/x.spy:2:12
  2 |     return 1 + "hello"
    |            |_________| operator::ADD called here

I think it would be nice to include the function name (or even better, the FQN) in the error message. Something like this:

❯ spy /tmp/x.spy 
TypeError: cannot do `i32` + `str`
  In function `x::foo`:
   --> /tmp/x.spy:2:12
  2 |     return 1 + "hello"
    |            ^ this is `i32`

   --> /tmp/x.spy:2:16
  2 |     return 1 + "hello"
    |                |_____| this is `str`

   --> /tmp/x.spy:2:12
  2 |     return 1 + "hello"
    |            |_________| operator::ADD called here

I honestly don't know what is the best way to present/format it, I'm open to suggestion. I think it would be good to see what other "modern" compilers do in similar cases (e.g. rust, zig, go).

[antocuni]

One example of why we need a better error message is in this comment:
#172 (comment)