CostModel lookup failures related to LazyValue.
CostModel lookup failures related to LazyValue.

Fixes root-cause of GitHub issue #309
https://github.com/tlaplus/tlaplus/issues/309

[Bug][TLC]
tlaplus/tlaplus,lemmy/tlaplus,tlaplus/tlaplus,lemmy/tlaplus,lemmy/tlaplus,lemmy/tlaplus,tlaplus/tlaplus,tlaplus/tlaplus