The go wasm process exiting is a sign of an unhandled panic. Also
add a explicit recover() call in the notify callback, that's where most
logic bugs are likely to happen (and they may not be fatal).
Also fixes the one panic that was encountered (nill pointer dereference
when generating the JS view of the netmap).
Fixes#5132
Signed-off-by: Mihai Parparita <mihai@tailscale.com>
Mihai Parparita
a3d74c4548