REACH-82 "Null value cannot be cast to double"

When Number node is created it has `Value` is `null`. And only rendering causes updating it to `"0"`. Or changing `Value` from "0" to another number. That's why in headless mode when we created node number without changing its value (we need exactly "0") and connect it with another node, running is failed because that other node needs number rather than `null`
This code belongs to `DynamoWebServer` project that is absent in `master` branch