[BUG] Beacon sender reports error for success when diagnostics are enabled

[johnc-ftl]

I had to enable:

  loggingLevelConsole: 2

to troubleshoot an issue I'm encountering (duplicate telemetry being reported), and it turns out that a failure message is always reported every time the beacon sender is used to send telemetry, even when the request is successfully queued. I receive console warning messages like:

AI (Internal): 26 message:"Failed to send telemetry." props:"(request payload)"

every time telemetry is sent, even though the request was successful.

Screenshot of callstack plus one of the problematic functions:

It appears that this issue was introduced by:
f4da17e#diff-d1f29788d9390adbc9ff2f85e60bf370be120a7985298d0657fea9ff831e5322

though I'm not 100% confident in stating that. Obviously there aren't tests to verify correct error reporting for this case.

In Sender.ts, after the beacon is successfully queued the payload is sent to oncomplete as the response:

In _getOnComplete() if there is a response, whether or not the status code is 200 an error is reported:

Steps to Reproduce

SDK Version:
"name": "@microsoft/applicationinsights-channel-js",
"version": "3.0.5"

Configuration:

  // Prefer beacon API for tracking
  isBeaconApiDisabled: false,
  loggingLevelConsole: 2

Expected behavior

Beacon requests that succeed don't result in reported errors, when diagnostics is enabled.