fix: usize conversion

Co-authored-by: Joel Dice <[email protected]>

crates/guest-rust/rt/src/async_support.rs

@@ -344,7 +344,8 @@ impl ErrorContext {
             unsafe {
                 let mut ret = [0u32; 2];
                 error_context_debug_message(self.handle, ret.as_mut_ptr() as *mut _);
-                String::from_raw_parts(ret[0] as *mut _, ret[1] as usize, ret[1] as usize)
+                let len = usize::try_from(ret[1]).unwrap();
+                String::from_raw_parts(usize::try_from(ret[0]).unwrap() as *mut _, len, len)
             }
         }
     }