Fix another type error

Author: Mrtenz

packages/snaps-cli/src/commands/watch/implementation.ts

@@ -1,3 +1,4 @@
+import { assert } from '@metamask/utils';
 import { basename } from 'path';
 import type { Watching } from 'webpack';
 
@@ -39,6 +40,11 @@ export async function watch(
           return;
         }
 
+        assert(
+          compiler.watching,
+          'Expected `compiler.watching` to be defined.',
+        );
+
         resolve(compiler.watching);
       },
     );

packages/snaps-cli/src/webpack/plugins.ts

@@ -5,7 +5,6 @@ import type { Ora } from 'ora';
 import type {
   Compiler,
   ProvidePlugin,
-  ResolvePluginInstance,
   Resolver,
   StatsError,
   WebpackPluginInstance,
@@ -231,6 +230,13 @@ export class SnapsWatchPlugin implements WebpackPluginInstance {
   }
 }
 
+/**
+ * Webpack's resolver plugin interface, which is not exported by Webpack.
+ */
+type ResolverPlugin = {
+  apply: (resolver: Resolver) => void;
+};
+
 /**
  * The options for the {@link SnapsBuiltInResolver}.
  */
@@ -247,7 +253,7 @@ export type SnapsBuiltInResolverOptions = {
  * plugin is used to warn the user when they try to import a built-in module,
  * when no fallback is configured.
  */
-export class SnapsBuiltInResolver implements ResolvePluginInstance {
+export class SnapsBuiltInResolver implements ResolverPlugin {
   /**
    * The built-in modules that have been imported, but not resolved.
    */