Update 'noExperiments' context after trace open

[williamsyang-work]

What it does

Fixes #296.
Triggers an update to the 'trace-explorer.noExperiments' context after a trace or experiment is opened.

How to test

The steps to reproduce the bug can be found in #296.
The bug can be reproduced on master
The bug should be fixed on this branch.

Follow-ups

When the server is online, the context is properly updated by a vscode-message sent from the frontend recieved by the backend.

Frontend:

// 105-112 vscode-trace-explorer-opened-traces-widget.tsx
private initialized = false;
protected doHandleOpenedTracesChanged(payload: OpenedTracesUpdatedSignalPayload): void {
    if (!this.initialized) {
        this.initialized = true;
        return;
    }
    this._signalHandler.updateOpenedTraces(payload.getNumberOfOpenedTraces());
}

Backend:

// 116-118 trace-explorer-opened-traces-webview-provider.ts
case VSCODE_MESSAGES.OPENED_TRACES_UPDATED:
    updateNoExperimentsContext();
    return;

I'm not sure why this code is triggered when the server is online and not when the server is offline. I didn't dig too deep into investigating that because I'm not sure the relevancy, and I know that the events getting bounced around on the FE / BE can get really messy and hard to trace.

There is also the tracking of initialized and we may simply not be sending the first signal intentionally. This can be investigated because it may not be necessary to track anymore and could lead a cleaner solution.

I didn't deep dive into this. I think updating the context on the backend after a trace is opened is a reasonable approach. WDYT?

Review checklist

• [x ] As an author, I have thoroughly tested my changes and carefully followed the instructions in this template

[marcdumais-work]

That's a creative way of ensuring to update that context after that "leaky" block executes, without adding it in a bunch of places - I like

[marcdumais-work]

LGTM - thanks for this contribution!

[marcdumais-work]

I think updating the context on the backend after a trace is opened is a reasonable approach. WDYT?

seems reasonable to me

[bhufmann]

Looks good to me. This change fixed it. Thanks!