Standardize on {}|void instead of ?{} options.

packages/babel-core/src/config/option-manager.js

@@ -214,7 +214,7 @@ class OptionManager {
 
 type BasicDescriptor = {
   value: {} | Function,
-  options: ?{},
+  options: {} | void,
   dirname: string,
   alias: string,
   loc: string,
@@ -222,7 +222,7 @@ type BasicDescriptor = {
 
 type LoadedDescriptor = {
   value: {},
-  options: ?{},
+  options: {} | void,
   dirname: string,
   alias: string,
   loc: string,
@@ -520,7 +520,7 @@ function normalizePair(
 ): {
   filepath: string | null,
   value: {} | Function,
-  options: ?{},
+  options: {} | void,
 } {
   let options;
   let value = pair;
@@ -562,6 +562,7 @@ function normalizePair(
       "Plugin/Preset options must be an object, null, or undefined",
     );
   }
+  options = options || undefined;
 
   return { filepath, value, options };
 }

packages/babel-core/src/config/plugin.js

@@ -9,7 +9,7 @@ export default class Plugin {
 
   options: {} | void;
 
-  constructor(plugin: {}, options: ?{}, key?: string) {
+  constructor(plugin: {}, options: {} | void, key?: string) {
     if (plugin.name != null && typeof plugin.name !== "string") {
       throw new Error("Plugin .name must be a string, null, or undefined");
     }
@@ -37,6 +37,6 @@ export default class Plugin {
     this.post = plugin.post;
     this.pre = plugin.pre;
     this.visitor = plugin.visitor;
-    this.options = options || undefined;
+    this.options = options;
   }
 }