optimize: avoid generating drop glue for StepResult

fix-vm/src/instructions/collections.rs

@@ -63,9 +63,9 @@ impl<'gc> crate::Vm<'gc> {
 
         let attrs = self.peek_stack(0).restrict().expect("forced");
         let Some(attrset) = attrs.as_gc::<AttrSet>() else {
-            return StepResult::Done(Err(Error::eval_error(
+            return self.finish_err(Error::eval_error(
                 "value is not a set while a set was expected",
-            )));
+            ));
         };
 
         match attrset.lookup(key) {
@@ -85,9 +85,9 @@ impl<'gc> crate::Vm<'gc> {
                         break;
                     } else {
                         let name = ctx.resolve_string(key);
-                        return StepResult::Done(Err(Error::eval_error(format!(
+                        return self.finish_err(Error::eval_error(format!(
                             "attribute '{name}' missing"
-                        ))));
+                        )));
                     }
                 }
             }
@@ -119,16 +119,16 @@ impl<'gc> crate::Vm<'gc> {
         } else if let Some(ns) = key_val.as_gc::<NixString>() {
             ctx.intern_string(ns.as_str())
         } else {
-            return StepResult::Done(Err(Error::eval_error(
+            return self.finish_err(Error::eval_error(
                 "dynamic select key must be a string",
-            )));
+            ));
         };
 
         let attrset_val = self.stack[self.stack.len() - 2].restrict().expect("forced");
         let Some(attrset) = attrset_val.as_gc::<AttrSet>() else {
-            return StepResult::Done(Err(Error::eval_error(
+            return self.finish_err(Error::eval_error(
                 "value is not a set while a set was expected",
-            )));
+            ));
         };
 
         match attrset.lookup(key_sid) {
@@ -138,9 +138,9 @@ impl<'gc> crate::Vm<'gc> {
             }
             None => {
                 let name = ctx.resolve_string(key_sid);
-                return StepResult::Done(Err(Error::eval_error(format!(
+                return self.finish_err(Error::eval_error(format!(
                     "attribute '{name}' missing"
-                ))));
+                )));
             }
         }
         StepResult::Continue