Remove MethodChannelPermissionHandler

permission_handler_platform_interface/lib/permission_handler_platform_interface.dart

@@ -3,7 +3,6 @@ library permission_handler_platform_interface;
 import 'dart:async';
 import 'package:meta/meta.dart';
 import 'package:plugin_platform_interface/plugin_platform_interface.dart';
-import 'src/method_channel/method_channel_permission_handler.dart';
 
 part 'src/permission_handler_platform_interface.dart';
 part 'src/permission_status.dart';

permission_handler_platform_interface/lib/src/permission_handler_platform_interface.dart

@@ -18,21 +18,21 @@ abstract class PermissionHandlerPlatform extends PlatformInterface {
 
   /// The instance of [PermissionHandlerPlatform] to use.
   ///
-  /// Returns:
-  /// - The instance, if it has been created, or
-  /// - A newly created instance through the builder provided in
-  /// [setInstanceBuilder], or
-  /// - A default, platform-specific implementation of
-  /// [PermissionHandlerPlatform], as [MethodChannelPermissionHandler].
+  /// Returns the instance, if it has been created, or a newly created instance
+  /// through the builder provided in [setInstanceBuilder]. Throws an
+  /// [Exception] if there is no instance, and [setInstanceBuilder] has not been
+  /// called.
   static PermissionHandlerPlatform get instance {
     if (_instance == null) {
-      if (_instanceBuilder != null) {
-        _instance = _instanceBuilder!();
-        PlatformInterface.verifyToken(_instance!, _token);
-      } else {
-        _instance = MethodChannelPermissionHandler();
+      if (_instanceBuilder == null) {
+        throw Exception(
+            'No instance builder was provided. Did you call `setInstanceBuilder`?');
       }
+
+      _instance = _instanceBuilder!();
+      PlatformInterface.verifyToken(_instance!, _token);
     }
+
     return _instance!;
   }