Validate that URL previews are explicitly enabled/disabled

Otherwise `!null` ends up being "true", therefore forcing URL previews on for everyone.

Fixes https://github.com/vector-im/riot-web/issues/5607

Signed-off-by: Travis Ralston <travpc@gmail.com>

src/settings/handlers/AccountSettingsHandler.js

@@ -26,6 +26,9 @@ export default class AccountSettingHandler extends SettingsHandler {
         // Special case URL previews
         if (settingName === "urlPreviewsEnabled") {
             const content = this._getSettings("org.matrix.preview_urls");
+
+            // Check to make sure that we actually got a boolean
+            if (typeof(content['disable']) !== "boolean") return null;
             return !content['disable'];
         }
 

src/settings/handlers/RoomAccountSettingsHandler.js

@@ -25,6 +25,9 @@ export default class RoomAccountSettingsHandler extends SettingsHandler {
         // Special case URL previews
         if (settingName === "urlPreviewsEnabled") {
             const content = this._getSettings(roomId, "org.matrix.room.preview_urls");
+
+            // Check to make sure that we actually got a boolean
+            if (typeof(content['disable']) !== "boolean") return null;
             return !content['disable'];
         }
 

src/settings/handlers/RoomSettingsHandler.js

@@ -25,6 +25,9 @@ export default class RoomSettingsHandler extends SettingsHandler {
         // Special case URL previews
         if (settingName === "urlPreviewsEnabled") {
             const content = this._getSettings(roomId, "org.matrix.room.preview_urls");
+
+            // Check to make sure that we actually got a boolean
+            if (typeof(content['disable']) !== "boolean") return null;
             return !content['disable'];
         }