Fix TypeError: Cannot read property 'isGuest' of undefined

react/features/base/config/reducer.js

         // The config of INITIAL_STATE is meant to override the config
         // downloaded from the Jitsi Meet deployment because the former contains
         // values that are mandatory.
+        //
+        // FIXME At the time of this writing the hard-coded overriding values
+        // are specific to mobile/React Native but the source code here is
+        // executed on Web/React as well. The latter is not a practical problem
+        // right now because the rest of the Web/React source code does not read
+        // the overridden properties/values, it still relies on the global
+        // variable config.
         ...INITIAL_STATE
     };
 }

react/features/base/lib-jitsi-meet/actions.js

     return (dispatch: Dispatch<*>) => {
         dispatch({ type: LIB_WILL_DISPOSE });
 
-        // XXX We're wrapping it with Promise because:
-        // a) to be better aligned with initLib() method which is async;
-        // b) as currently there is no implementation for it in lib-jitsi-meet
-        //    and there is a big chance it will be async.
         // TODO Currently, lib-jitsi-meet doesn't have the functionality to
         // dispose itself.
-        return (
-            Promise.resolve()
-                .then(() => dispatch({ type: LIB_DID_DISPOSE })));
+        dispatch({ type: LIB_DID_DISPOSE });
     };
 }
 

react/features/base/lib-jitsi-meet/middleware.js

     // disposed of first.
     // TODO Currently, disposeLib actually does not dispose of lib-jitsi-meet
     // because lib-jitsi-meet does not implement such functionality.
-    const disposeLibPromise
-        = initialized ? dispatch(disposeLib()) : Promise.resolve();
-
-    disposeLibPromise.then(() => {
-        // Let the new config into the Redux store (because initLib will read it
-        // from there).
-        next(action);
-
-        // FIXME Obviously, the following is bad design. However, I'm currently
-        // introducing the features base/config and base/logging and I'm trying
-        // to minimize the scope of the changes while I'm attempting to preserve
-        // compatibility with the existing partially React-ified Web source code
-        // and what was already executing on React Native. Additionally, I do
-        // not care to load logging_config.js on React Native.
-        dispatch(setLoggingConfig(window.loggingConfig));
-
-        dispatch(initLib());
-    });
+    if (initialized) {
+        dispatch(disposeLib());
+    }
+
+    // Let the new config into the Redux store (because initLib will read it
+    // from there).
+    const result = next(action);
+
+    // FIXME Obviously, the following is bad design. However, I'm currently
+    // introducing the features base/config and base/logging and I'm trying to
+    // minimize the scope of the changes while I'm attempting to preserve
+    // compatibility with the existing partially React-ified Web source code and
+    // what was already executing on React Native. Additionally, I do not care
+    // to load logging_config.js on React Native.
+    dispatch(setLoggingConfig(window.loggingConfig));
+
+    dispatch(initLib());
+
+    return result;
 }

react/features/base/react/Platform.web.js

 /* @flow */
 
-const userAgent = navigator.userAgent;
+const { userAgent } = navigator;
 let OS;
 
 if (userAgent.match(/Android/i)) {

react/features/toolbox/actions.web.js

 export function showDialPadButton(show: boolean): Function {
     return (dispatch: Dispatch<*>) => {
         const buttonName = 'dialpad';
-        const shouldShow = UIUtil.isButtonEnabled(buttonName) && show;
 
-        if (shouldShow) {
+        if (show && UIUtil.isButtonEnabled(buttonName)) {
             dispatch(setToolbarButton(buttonName, {
                 hidden: false
             }));
 export function showSharedVideoButton(): Function {
     return (dispatch: Dispatch<*>) => {
         const buttonName = 'sharedvideo';
-        const shouldShow
-            = UIUtil.isButtonEnabled(buttonName)
-                && !config.disableThirdPartyRequests;
 
-        if (shouldShow) {
+        if (UIUtil.isButtonEnabled(buttonName)
+                && !config.disableThirdPartyRequests) {
             dispatch(setToolbarButton(buttonName, {
                 hidden: false
             }));
 }
 
 /**
- * Shows SIP call button if it's required and appropriate
- * flag is passed.
+ * Shows SIP call button if it's required and appropriate flag is passed.
  *
  * @param {boolean} show - Flag showing whether to show button or not.
  * @returns {Function}
  */
 export function showSIPCallButton(show: boolean): Function {
-    return (dispatch: Dispatch<*>) => {
+    return (dispatch: Dispatch<*>, getState: Function) => {
         const buttonName = 'sip';
 
-        // hide the button if there is a config to check for user roles,
-        // based on the token and the the user is guest
-        const shouldShow
-            = APP.conference.sipGatewayEnabled()
+        if (show
+                && APP.conference.sipGatewayEnabled()
                 && UIUtil.isButtonEnabled(buttonName)
-                && show
                 && (!config.enableUserRolesBasedOnToken
-                        || !APP.tokenData.isGuest);
-
-        if (shouldShow) {
+                    || !getState()['features/jwt'].isGuest)) {
             dispatch(setToolbarButton(buttonName, {
-                hidden: !shouldShow
+                hidden: false
             }));
         }
     };