refactor: encapsulate Drop passthrough in createScope

src/context/context.ts

@@ -95,7 +95,7 @@ export class Context {
     return scope
   }
   public push (ctx: Scope): Scope {
-    const scope = ctx instanceof Drop ? ctx : createScope(ctx)
+    const scope = createScope(ctx)
     this.scopes.push(scope)
     return scope
   }

src/context/scope.ts

@@ -6,6 +6,7 @@ export interface ScopeObject extends Record<string | number | symbol, any> {
 
 export type Scope = ScopeObject | Drop
 
-export function createScope (from?: ScopeObject): ScopeObject {
+export function createScope (from?: Scope): Scope {
+  if (from instanceof Drop) return from
   return Object.assign(Object.create(null), from)
 }