diff --git a/web/src/blueslip.ts b/web/src/blueslip.ts
index 66c8dbe698..387e96fb9a 100644
--- a/web/src/blueslip.ts
+++ b/web/src/blueslip.ts
@@ -85,7 +85,7 @@ export function warn(msg: string, more_info?: unknown): void {
     }
 }
 
-export function error(msg: string, more_info?: object | undefined, original_error?: unknown): void {
+export function error(msg: string, more_info?: object, original_error?: unknown): void {
     // Log the Sentry error before the console warning, so we don't
     // end up with a doubled message in the Sentry logs.
     Sentry.setContext("more_info", more_info ?? null);
diff --git a/web/src/blueslip_stacktrace.ts b/web/src/blueslip_stacktrace.ts
index 9907edde03..48bd726ac0 100644
--- a/web/src/blueslip_stacktrace.ts
+++ b/web/src/blueslip_stacktrace.ts
@@ -8,7 +8,7 @@ import render_blueslip_stacktrace from "../templates/blueslip_stacktrace.hbs";
 export class BlueslipError extends Error {
     override name = "BlueslipError";
     more_info?: object;
-    constructor(msg: string, more_info?: object | undefined, cause?: unknown) {
+    constructor(msg: string, more_info?: object, cause?: unknown) {
         super(msg, {cause});
         if (more_info !== undefined) {
             this.more_info = more_info;
diff --git a/web/src/email_pill.ts b/web/src/email_pill.ts
index 3106851033..ba22e8c0a4 100644
--- a/web/src/email_pill.ts
+++ b/web/src/email_pill.ts
@@ -45,7 +45,7 @@ export function get_current_email(
 
 export function create_pills(
     $pill_container: JQuery,
-    pill_config?: InputPillConfig | undefined,
+    pill_config?: InputPillConfig,
 ): input_pill.InputPillContainer<EmailPill> {
     const pill_container = input_pill.create({
         $container: $pill_container,
diff --git a/web/src/emoji_picker.ts b/web/src/emoji_picker.ts
index 56d7ee4a41..0982250b1d 100644
--- a/web/src/emoji_picker.ts
+++ b/web/src/emoji_picker.ts
@@ -711,7 +711,7 @@ function get_default_emoji_popover_options(): Partial<tippy.Props> {
 
 export function toggle_emoji_popover(
     target: tippy.ReferenceElement,
-    id?: number | undefined,
+    id?: number,
     additional_popover_options?: Partial<tippy.Props>,
 ): void {
     if (id) {
diff --git a/web/src/input_pill.ts b/web/src/input_pill.ts
index c47c18a998..7ae041484b 100644
--- a/web/src/input_pill.ts
+++ b/web/src/input_pill.ts
@@ -25,7 +25,7 @@ type InputPillCreateOptions<ItemType> = {
     create_item_from_text: (
         text: string,
         existing_items: ItemType[],
-        pill_config?: InputPillConfig | undefined,
+        pill_config?: InputPillConfig,
     ) => ItemType | undefined;
     get_text_from_item: (item: ItemType) => string;
     get_display_value_from_item: (item: ItemType) => string;
diff --git a/web/src/user_pill.ts b/web/src/user_pill.ts
index 20e26a82ab..30070f6e70 100644
--- a/web/src/user_pill.ts
+++ b/web/src/user_pill.ts
@@ -38,7 +38,7 @@ export type UserPillData = {type: "user"; user: User};
 export function create_item_from_email(
     email: string,
     current_items: CombinedPill[],
-    pill_config?: InputPillConfig | undefined,
+    pill_config?: InputPillConfig,
 ): UserPill | undefined {
     // For normal Zulip use, we need to validate the email for our realm.
     const user = people.get_by_email(email);
@@ -217,7 +217,7 @@ export function generate_pill_html(item: UserPill, show_user_status_emoji = fals
 
 export function create_pills(
     $pill_container: JQuery,
-    pill_config?: InputPillConfig | undefined,
+    pill_config?: InputPillConfig,
 ): input_pill.InputPillContainer<UserPill> {
     const pills = input_pill.create({
         $container: $pill_container,