Cannot read property 'toLowerCase' of null

[lldata]

• VSCode Version: 1.22.2
• OS Version: win7
• REST Client Version: 0.18.4

After running VS Code REST client for a while, I get this error when trying to call any REST service.
"Cannot read property 'toLowerCase' of null".

I can't reproduce it. It just happens every couple of hours or days.
Closing the http file does not resolve it. Only restarting VSCode resolves the issue.

It is quite annoying. I'd like to provide more information, but I don't know where to start.
I get the feeling that the toLowerCase hides another error.

[Huachao]

@lldata can you show me your http file? And do you mean for same http request, after restarting VS Code can succeed?

And when you are in error state, can you succeed sending a simple request in another file like GET https://www.google.com.

Do you have a callstack in this case, and the notificationAlerts.ts is the code from vscode itself

[lldata]

When I am in the error state ALL requests fail. So I don't think my http file is that important.
I am reluctant to send it since it uses internal API's.

After restarting all requests resume working as expected.

I will attempt to produce a call stack next time I hit the error, but I am not sure how I get it?

[Huachao]

@lldata since retarting can work, maybe it is related to something that keep in memory of the extension lifetime. One thing I can think of is request variable cache. I will continue inspecting this tomorrow.

[lldata]

Sounds likely. I use request variables extensively. Something related to caching or other mutable state seems very likely. But it might be hard to fix, if you can't reproduce it ;-)

[Huachao]

@lldata I checked all the code used the toLowerCase() method, I can't find any risk code to call this function. And I want to confirm with you for some possibilities.

• Can you show me all the named requests'(requests that are referenced by other requests) response content type header value. Or even if some of the responses don't have Content-Type header in them?
• What's your setting value for rest-client.previewOption?
• Do you use proxy setting rest-client.excludeHostsForProxy?
• Do ALL requests failed use requests, if so, try to hover on the references places in request to see if any error occurs.
• If you don't send any request, just open the http file, will the same error happens?

Thanks in advance.

[lldata]

• I have never noticed a response without Content-Type header. I am pretty sure we have that always.
• "rest-client.previewOption": "full" (default)
• Yes! We use a proxy server
• The errors only occurs when I click the request links

When I first got the error some time ago, I dived into the VSCode debugger and caught the error there.
To me it looks like vs code is trying to do a toLowerCase on something - presumably an error from a lower layer. I'll try to catch it again, when I see it next time.

[Huachao]

@lldata so do you mean the error actually happens in the code from VSCode, not from my extension directly?

[lldata]

From the debug session my impression was that the toLowerCase call was somewhere in the VSCode code base. But to me it looked like there was a different error below.
Also it only happens when I use the rest-client and only when I click "Send request".
I think it is safe to assume that the error is in your plugin. But it might not be in a toLowerCase call.
Look for mutable state. Variables. Request caches. Race conditions.

[Huachao]

@lldata how did you go into the debug session of vscode? Do all requests reference the same request? BTW, can you try to copy the request as cURL(right click for the selected request) when you meet the situation again and check if any error occurs.

[lldata]

I managed to reproduce it and get this Call Stack:

e.onDidNotificationChange (notificationsAlerts.ts:39) (anonymous) (notificationsAlerts.ts:28) e.fire (event.ts:140) e.notify (notifications.ts:127) e.notify (notificationService.ts:65) (anonymous) (mainThreadMessageService.ts:86) e._showMessage (mainThreadMessageService.ts:47) e.$showMessage (mainThreadMessageService.ts:41) e._doInvokeHandler (rpcProtocol.ts:174) e._invokeHandler (rpcProtocol.ts:159) e._receiveRequest (rpcProtocol.ts:108) e._receiveOneMessage (rpcProtocol.ts:90) (anonymous) (rpcProtocol.ts:33) (anonymous) (rpcProtocol.ts:213) e.fire (event.ts:140) (anonymous) (ipc.net.ts:81) emitOne (events.js:96) emit (events.js:191) readableAddChunk (_stream_readable.js:178) Readable.push (_stream_readable.js:136) onread (net.js:560)

[lldata]

I just spent some time browsing around the debugger. It seems that the question is: who calls onread.
I think some kind of event/exception is emitted from some code that does not show up in the Call Stack.
"onread" in net.js is an event handler.

About the only useful thing I could find is that the event is from the restclient plugin:

[Huachao]

@lldata Uhh... Thanks for your help. And can you have a clear repro step for me to help me to investigate? Like showing me after sending a request 'A' and then request 'B' will no longer work until you restart vscode.

[lldata]

I am sorry. I can't reproduce it at will.
It just happens - then I restart and it works again ..

[Huachao]

@lldata can you try to repro this issue in latest version 0.19.0, and I add some error log in output channel. Thanks in advance.

[lldata]

Thank you. I have updated and will investigate next time I can reproduce it.

[Huachao]

@lldata did you meet this problem recently?

[lldata]

Yeah. One of my colleagues got it while I helped him this week.
He was on the latest version.

Only one request in his file didn't work. The others worked fine.
We modied another request in the file, to be exactly the same and that worked.
So I am guessing that the error is somehow connected to the internal state the plugin keeps in relation to a request.

[Huachao]

@lldata next time you meet the issue, please help to check the REST output channel of VSCode, more error details are logged there

[Huachao]

@lldata sorry to bother you again, please help to check if this still happens in latest version like 0.20.2, if yes, please help to inspect the output channel of VSCode with channel name REST. Thanks in advance.

[lldata]

We managed to reproduce it. My collegues report that they can reproduce it consistently by copying requests from Skype and into a .rest file.

Here is the output from the debug channel:

TypeError: Cannot read property 'toLowerCase' of null
TypeError: Cannot read property 'toLowerCase' of null
	at Function.ignoreProxy (C:\Users\wql\.vscode\extensions\humao.rest-client-0.20.1\out\src\utils\httpClient.js:238:45)
	at HttpClient.<anonymous> (C:\Users\wql\.vscode\extensions\humao.rest-client-0.20.1\out\src\utils\httpClient.js:158:53)
	at Generator.next (<anonymous>)
	at C:\Users\wql\.vscode\extensions\humao.rest-client-0.20.1\out\src\utils\httpClient.js:7:71
	at new Promise (<anonymous>)
	at __awaiter (C:\Users\wql\.vscode\extensions\humao.rest-client-0.20.1\out\src\utils\httpClient.js:3:12)
	at HttpClient.prepareOptions (C:\Users\wql\.vscode\extensions\humao.rest-client-0.20.1\out\src\utils\httpClient.js:108:16)
	at HttpClient.<anonymous> (C:\Users\wql\.vscode\extensions\humao.rest-client-0.20.1\out\src\utils\httpClient.js:44:40)
	at Generator.next (<anonymous>)
	at C:\Users\wql\.vscode\extensions\humao.rest-client-0.20.1\out\src\utils\httpClient.js:7:71
	at new Promise (<anonymous>)
	at __awaiter (C:\Users\wql\.vscode\extensions\humao.rest-client-0.20.1\out\src\utils\httpClient.js:3:12)
	at HttpClient.send (C:\Users\wql\.vscode\extensions\humao.rest-client-0.20.1\out\src\utils\httpClient.js:43:16)
	at RequestController.<anonymous> (C:\Users\wql\.vscode\extensions\humao.rest-client-0.20.1\out\src\controllers\requestController.js:126:55)
	at Generator.next (<anonymous>)
	at C:\Users\wql\.vscode\extensions\humao.rest-client-0.20.1\out\src\controllers\requestController.js:13:71
	at new Promise (<anonymous>)
	at __awaiter (C:\Users\wql\.vscode\extensions\humao.rest-client-0.20.1\out\src\controllers\requestController.js:9:12)
	at RequestController.runCore (C:\Users\wql\.vscode\extensions\humao.rest-client-0.20.1\out\src\controllers\requestController.js:119:16)
	at RequestController.<anonymous> (C:\Users\wql\.vscode\extensions\humao.rest-client-0.20.1\out\src\controllers\requestController.js:94:24)
	at Generator.next (<anonymous>)
	at fulfilled (C:\Users\wql\.vscode\extensions\humao.rest-client-0.20.1\out\src\controllers\requestController.js:10:58)
	at <anonymous>

[Huachao]

@lldata Thanks so much @lldata. I can reproduce this issue as illustrated in the call stack, which needs to meet all the following three preconditions:

1. Set the http.proxy setting
2. Set the rest-client.excludeHostsForProxy setting
3. The request url is not in a well defined format, like missing protocol, etc.,

Anyway, I will fix this issue ASAP to handle this case. Really a nice catch 👍

[Huachao]

@lldata I will publish this fix in next release.

[lldata]

Amazing feedback time 💯 👍

Thank you for your work!

[Huachao]

@lldata I have published the new version 0.20.3, and you can verify it. And if you still meet this issue, don't hesitate to contact me.