Consolidate Settings
Consolidate the various places where one cat set the instrumentation key. I just found that my app had two different keys:
APPINSIGHTS_INSTRUMENTATIONKEY
ApplicationInsights:InstrumentationKey
One set by the portal, which I think is for the debugger, snapshots, more integrated solutions and the other one is set by me or VS at install into the app. This is the one that I would typically use to embed for JS and (in some cases) manually at startup for the app.
There's also the config file, it seems (I don;t use that). There should be one place to ensure that the correct key is used and throw an exception (or don;t report data) if it's not set there.

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