The master branch used extension.id instead of extension.metadata['Name']

for some of the logged messages when extensions threw exceptions. This failed

with the SandboxExtension used in the unit tests, since the id is assigned by

ExtensionManager.load(), and only for extensions with entry points.
I've manually assigned an extension ID to the SandboxExtension, and updated

the other sandbox log messages to be consistent.

Ran unit tests.