Log warning if Vue app is mounted before Sentry.init is called

[Lms24]

Problem Statement

As explained in our Vue docs, Sentry.init should be called before a Vue 2 or 3 app is mounted (app.mount("#app")). The reason is that our SDK needs to initialize itself and instrument various handlers before the actual Vue app is bootstrapped. If this happens in the opposite order, Sentry cannot detect errors that happen during mounting.

Solution Brainstorm

We need some way to check in Sentry.init if the app object (which we pass to the init function) was already mounted. Perhaps this object has some property that is changed on mount or we could check for hooks in some way. Not yet sure.

This is not high-prio but it'd be nice to have when we get to it.