When a template contains a binding without a value, the template parser
creates an `EmptyExpr` node. This would previously be translated into
an `undefined` value, which would cause a crash downstream as `undefined`
is not included in the allowed type, so it was not handled properly.
This commit prevents the crash by returning an actual expression for empty
bindings.
Fixes#30076Fixes#30929
PR Close#31594
0db1b5d8f1