Merge pull request #334 from ichiban/avoid-recursive-load

avoid recursive file load.

engine/text.go

@@ -192,11 +192,16 @@ func (vm *VM) ensureLoaded(ctx context.Context, file Term, env *Env) error {
 	if _, ok := vm.loaded[f]; ok {
 		return nil
 	}
-	defer func() {
-		vm.loaded[f] = struct{}{}
-	}()
 
-	return vm.Compile(ctx, string(b))
+	// It's too early to say it's fully loaded. Yet this avoids recursive load of the same file.
+	vm.loaded[f] = struct{}{}
+
+	if err := vm.Compile(ctx, string(b)); err != nil {
+		delete(vm.loaded, f) // It wasn't fully loaded after all.
+		return err
+	}
+
+	return nil
 }
 
 func (vm *VM) open(file Term, env *Env) (string, []byte, error) {