wasm_interp: fix a bug in implicit return

crates/wasm_interp/src/call_stack.rs

@@ -178,7 +178,7 @@ impl<'a> CallStack<'a> {
     }
 
     pub fn is_empty(&self) -> bool {
-        self.is_64.is_empty()
+        self.frame_offsets.is_empty()
     }
 
     /// Dump a stack trace of the WebAssembly program

crates/wasm_interp/src/instance.rs

@@ -12,6 +12,7 @@ use crate::call_stack::CallStack;
 use crate::value_stack::ValueStack;
 use crate::{Error, ImportDispatcher};
 
+#[derive(Debug)]
 pub enum Action {
     Continue,
     Break,