3 files changed, 33 insertions, 9 deletions
diff --git a/ext/js/display/display-anki.js b/ext/js/display/display-anki.js
index fb7bd85f..9a6b96c7 100644
--- a/ext/js/display/display-anki.js
+++ b/ext/js/display/display-anki.js
@@ -376,6 +376,7 @@ export class DisplayAnki {
     _updateAdderButtons(dictionaryEntryDetails) {
         const displayTags = this._displayTags;
         for (let i = 0, ii = dictionaryEntryDetails.length; i < ii; ++i) {
+            /** @type {?Set<number>} */
             let allNoteIds = null;
             for (const {mode, canAdd, noteIds, noteInfos, ankiError} of dictionaryEntryDetails[i].modeMap.values()) {
                 const button = this._adderButtonFind(i, mode);
diff --git a/ext/js/display/display-history.js b/ext/js/display/display-history.js
index 67690219..bc4f1539 100644
--- a/ext/js/display/display-history.js
+++ b/ext/js/display/display-history.js
@@ -37,9 +37,15 @@ export class DisplayHistory extends EventDispatcher {
         this._historyMap = new Map();
 
         const historyState = history.state;
-        const {id, state} = isObject(historyState) ? historyState : {id: null, state: null};
+        const {id, state} = (
+            typeof historyState === 'object' && historyState !== null ?
+            historyState :
+            {id: null, state: null}
+        );
+        /** @type {?import('display-history').EntryState} */
+        const stateObject = typeof state === 'object' || state === null ? state : null;
         /** @type {import('display-history').Entry} */
-        this._current = this._createHistoryEntry(id, location.href, state, null, null);
+        this._current = this._createHistoryEntry(id, location.href, stateObject, null, null);
     }
 
     /** @type {?import('display-history').EntryState} */
diff --git a/ext/js/display/display.js b/ext/js/display/display.js
index 750e0d69..f6efb5ac 100644
--- a/ext/js/display/display.js
+++ b/ext/js/display/display.js
@@ -1934,20 +1934,28 @@ export class Display extends EventDispatcher {
         this._hotkeyHandler.setHotkeys(this._pageType, options.inputs.hotkeys);
     }
 
-    /** */
-    async _closeTab() {
-        const tab = await new Promise((resolve, reject) => {
+    /**
+     * @returns {Promise<?chrome.tabs.Tab>}
+     */
+    _getCurrentTab() {
+        return new Promise((resolve, reject) => {
             chrome.tabs.getCurrent((result) => {
                 const e = chrome.runtime.lastError;
                 if (e) {
                     reject(new Error(e.message));
                 } else {
-                    resolve(result);
+                    resolve(typeof result !== 'undefined' ? result : null);
                 }
             });
         });
-        const tabId = tab.id;
-        await /** @type {Promise<void>} */ (new Promise((resolve, reject) => {
+    }
+
+    /**
+     * @param {number} tabId
+     * @returns {Promise<void>}
+     */
+    _removeTab(tabId) {
+        return new Promise((resolve, reject) => {
             chrome.tabs.remove(tabId, () => {
                 const e = chrome.runtime.lastError;
                 if (e) {
@@ -1956,7 +1964,16 @@ export class Display extends EventDispatcher {
                     resolve();
                 }
             });
-        }));
+        });
+    }
+
+    /** */
+    async _closeTab() {
+        const tab = await this._getCurrentTab();
+        if (tab === null) { return; }
+        const tabId = tab.id;
+        if (typeof tabId === 'undefined') { return; }
+        await this._removeTab(tabId);
     }
 
     /** */