[BUGFIX beta] add assertion against dynamic {{input type}}

Closes #5047
Merge pull request #5068 from amiel/input-type-nondynamic-warning

[BUGFIX beta] Add warning to variable {{input type}}, with working tests
[BUGFIX beta] Deprecate observing container views like arrays
[DOC beta] Mark Route#render options as optional
PromiseProxies should have content or a reason when settled

Fixes #5325
Merge pull request #5327 from gavacho/master

PromiseProxies should have content or a reason when settled