diff --git a/src/components/settings_modal/admin_tabs/emoji_tab.js b/src/components/settings_modal/admin_tabs/emoji_tab.js
index 7dc9e91bf..33ead7c16 100644
--- a/src/components/settings_modal/admin_tabs/emoji_tab.js
+++ b/src/components/settings_modal/admin_tabs/emoji_tab.js
@@ -122,7 +122,7 @@ const EmojiTab = {
             return this.refreshPackList()
           } else {
             this.displayError(resp.error)
-            return Promise.reject(resp)
+            throw new Error(resp)
           }
         })
         .then(() => {
@@ -139,7 +139,7 @@ const EmojiTab = {
             return this.refreshPackList()
           } else {
             this.displayError(resp.error)
-            return Promise.reject(resp)
+            throw new Error(resp)
           }
         })
         .then(() => {
@@ -239,7 +239,7 @@ const EmojiTab = {
             return this.refreshPackList()
           } else {
             this.displayError(resp.error)
-            return Promise.reject(resp)
+            throw new Error(resp)
           }
         })
         .then(() => {
@@ -259,7 +259,7 @@ const EmojiTab = {
             return this.refreshPackList()
           } else {
             this.displayError(resp.error)
-            return Promise.reject(resp)
+            throw new Error(resp)
           }
         })
         .then(() => {
@@ -280,7 +280,7 @@ const EmojiTab = {
             return this.refreshPackList()
           } else {
             this.displayError(resp.error)
-            return Promise.reject(resp)
+            throw new Error(resp)
           }
         })
         .then(() => {
diff --git a/src/components/settings_modal/helpers/emoji_editing_popover.vue b/src/components/settings_modal/helpers/emoji_editing_popover.vue
index d3db657d3..0cd04f053 100644
--- a/src/components/settings_modal/helpers/emoji_editing_popover.vue
+++ b/src/components/settings_modal/helpers/emoji_editing_popover.vue
@@ -262,7 +262,7 @@ export default {
         .then((resp) => {
           if (resp.error !== undefined) {
             this.$emit('displayError', resp.error)
-            return Promise.reject(resp.error)
+            throw new Error(resp.error)
           }
 
           return resp.json()
diff --git a/src/lib/persisted_state.js b/src/lib/persisted_state.js
index b4d6c596d..5fcf259aa 100644
--- a/src/lib/persisted_state.js
+++ b/src/lib/persisted_state.js
@@ -198,7 +198,7 @@ export const piniaPersistPlugin =
     const setState = (state) => {
       if (!loadedGuard.loaded) {
         console.info('waiting for old state to be loaded...')
-        return Promise.reject()
+        throw new Error('Waiting')
       } else {
         return storage.setItem(key, state)
       }
diff --git a/src/services/style_setter/style_setter.js b/src/services/style_setter/style_setter.js
index 4eed080c1..68e0632bf 100644
--- a/src/services/style_setter/style_setter.js
+++ b/src/services/style_setter/style_setter.js
@@ -359,11 +359,7 @@ export const getResourcesIndex = async (url, parser = (x) => x) => {
 
   const total = [...custom, ...builtin]
   if (total.length === 0) {
-    return Promise.reject(
-      new Error(
-        `Resource at ${url} and ${customUrl} completely unavailable. Panicking`,
-      ),
-    )
+    throw new Error(`Resource at ${url} and ${customUrl} completely unavailable. Panicking`)
   }
   return Promise.resolve(Object.fromEntries(total))
 }
diff --git a/src/services/sw/sw.js b/src/services/sw/sw.js
index 4f044c426..30c95406b 100644
--- a/src/services/sw/sw.js
+++ b/src/services/sw/sw.js
@@ -29,9 +29,9 @@ function getOrCreateServiceWorker() {
 
 function subscribePush(registration, isEnabled, vapidPublicKey) {
   if (!isEnabled)
-    return Promise.reject(new Error('Web Push is disabled in config'))
+    throw new Error('Web Push is disabled in config')
   if (!vapidPublicKey)
-    return Promise.reject(new Error('VAPID public key is not found'))
+    throw new Error('VAPID public key is not found')
 
   const subscribeOptions = {
     userVisibleOnly: false,
diff --git a/src/services/theme_data/theme2_to_theme3.js b/src/services/theme_data/theme2_to_theme3.js
index 5bab4818c..9ea319175 100644
--- a/src/services/theme_data/theme2_to_theme3.js
+++ b/src/services/theme_data/theme2_to_theme3.js
@@ -512,7 +512,7 @@ export const convertTheme2To3 = (data) => {
             { ...newRule, component: 'Tab' },
             { ...newRule, component: 'ScrollbarElement' },
           ]
-          if (newRule.state?.indexOf('toggled') >= 0) {
+          if (newRule.state?.includes('toggled')) {
             rules.push({ ...newRule, state: [...newRule.state, 'focused'] })
             rules.push({ ...newRule, state: [...newRule.state, 'hover'] })
             rules.push({
@@ -520,7 +520,7 @@ export const convertTheme2To3 = (data) => {
               state: [...newRule.state, 'hover', 'focused'],
             })
           }
-          if (newRule.state?.indexOf('hover') >= 0) {
+          if (newRule.state?.includes('hover')) {
             rules.push({ ...newRule, state: [...newRule.state, 'focused'] })
           }
           return rules
diff --git a/src/services/theme_data/theme_data_3.service.js b/src/services/theme_data/theme_data_3.service.js
index 626d7daeb..507b384db 100644
--- a/src/services/theme_data/theme_data_3.service.js
+++ b/src/services/theme_data/theme_data_3.service.js
@@ -690,11 +690,11 @@ export const init = ({
               .map((combination) => ['normal', ...combination])
               .filter((combo) => {
                 // Optimization: filter out some hard-coded combinations that don't make sense
-                if (combo.indexOf('disabled') >= 0) {
+                if (combo.includes('disabled')) {
                   return !(
-                    combo.indexOf('hover') >= 0 ||
-                    combo.indexOf('focused') >= 0 ||
-                    combo.indexOf('pressed') >= 0
+                    combo.includes('hover') ||
+                    combo.includes('focused') ||
+                    combo.includes('pressed')
                   )
                 }
                 return true
@@ -711,7 +711,7 @@ export const init = ({
       combination.component = component.name
       combination.lazy = component.lazy || parent?.lazy
       combination.parent = parent
-      if (!liteMode && combination.state.indexOf('hover') >= 0) {
+      if (!liteMode && combination.state.includes('hover')) {
         combination.lazy = true
       }