Not enough unreachability/side-effects tests

While a real compiler should never emit code like

(module
  (global $a (mut i32) (i32.const 0))

  (func (export "get-a") (result i32) (global.get $a))

  (func $set-and-return-a (result i32) (global.set $a (i32.const 1)) (global.get $a))

  (func (export "call-unreachable") (result i32)
    (call $set-and-return-a)
    (unreachable)
  )
)

(assert_trap (invoke "call-unreachable") "unreachable")
(assert_return (invoke "get-a") (i32.const 1))

it would be nice to see more tests like this.

The issue names no file or test entry point. Start with the WAST example and locate the existing WebAssembly tests for unreachability and side effects; add comparable cases and confirm they verify both the expected trap and side-effect result.