resolveUser: return null if the passed value is not a valid id

backend/src/plugins/Cases/functions/createCaseNote.ts

@@ -12,6 +12,10 @@ export async function createCaseNote(pluginData: PluginData<CasesPluginType>, ar
   }
 
   const mod = await resolveUser(pluginData.client, args.modId);
+  if (!mod) {
+    throw new RecoverablePluginError(ERRORS.INVALID_USER);
+  }
+
   const modName = `${mod.username}#${mod.discriminator}`;
 
   let body = args.body;

backend/src/plugins/ModActions/commands/UnmuteCmd.ts

@@ -35,6 +35,7 @@ export const UnmuteCmd = modActionsCommand({
   async run({ pluginData, message: msg, args }) {
     const user = await resolveUser(pluginData.client, args.user);
     if (!user) return sendErrorMessage(pluginData, msg.channel, `User not found`);
+
     const memberToUnmute = await resolveMember(pluginData.client, pluginData.guild, user.id);
     const mutesPlugin = pluginData.getPlugin(MutesPlugin);
     const hasMuteRole = memberToUnmute && mutesPlugin.hasMutedRole(memberToUnmute);

backend/src/plugins/ModActions/functions/banUserId.ts

@@ -20,6 +20,12 @@ export async function banUserId(
 ): Promise<BanResult> {
   const config = pluginData.config.get();
   const user = await resolveUser(pluginData.client, userId);
+  if (!user) {
+    return {
+      status: "failed",
+      error: "Invalid user",
+    };
+  }
 
   // Attempt to message the user *before* banning them, as doing it after may not be possible
   let notifyResult: UserNotificationResult = { method: null, success: true };

backend/src/plugins/Mutes/functions/muteUser.ts

@@ -41,6 +41,11 @@ export async function muteUser(
   }
 
   const user = await resolveUser(pluginData.client, userId);
+  if (!user) {
+    lock.unlock();
+    throw new RecoverablePluginError(ERRORS.INVALID_USER);
+  }
+
   const member = await resolveMember(pluginData.client, pluginData.guild, user.id); // Grab the fresh member so we don't have stale role info
   const config = pluginData.config.getMatchingConfig({ member, userId });