`onWillPatch`, `onWillUnmount`, `onWillDestroy` are synchronous hooks.
Owl will not wait any promise return by the callback.
Yet, the callback return type includes `Promise<void>`,
which is confusing as one might think it means the hooks is async.
Previously, when wrapping errors in wrapError, if the error was not an
actual error object, we wouldn't set the cause property on the wrapping
error correctly. The "instanceof Error" check is simply there so that we
can know whether we can add the original errors message to the wrapping
error, but the line that sets the error's cause was mistakenly moved
into that condition.
This commit also fixes the wrapping error's message in the case of
non-Error objects, to avoid having "the following error occurred in
hookname:" with nothing after the colon which is confusing/misleading.
This commit makes all errors thrown in owl use a custom error class. The
main point of this is to always wrap user-code errors that happen during
the owl lifecycle so that they can be treated uniformly in onError by
checking the cause property, and also allows user code to differenciate
owl errors from non-owl errors reliably at runtime.
Before this commit, wrapping an error occurring in async code
would result in an unhandledpromise exception, because we created
another promise, that would be rejected and that we didn't catch.
Julien Carion (juca)