network property
True when the exception is a failed network fetch — a
NetworkImageLoadException, typed rather than parsed out of the message.
A fact, not a verdict: what it means depends on the lane. In a live
guest it is a real request that really failed. Under flutter_test the
binding answers every HTTP request with 400, so there it says nothing
about the code — which is why the audit reads this to keep the
environment's failures from counting an entry broken.
Implementation
final bool network;