Error message
In the message, %s marks a value that the engine fills in when it raises the error.
The story
The engine stopped at birth because it could not read the file that describes its two heaps. Let me paint the picture. There is one big store, and inside it live two kinds of residents. The DataHeap holds inert values, things that just sit there. The ExecHeap holds verbs and flows, things that do work. Which one a being goes to depends on its Trinity kind, like a home assignment: nouns live in the DataHeap, verbs and flows live in the ExecHeap. The rules of that arrangement, which population is which, how their address spaces stay separate, and who owns the storage, are all written in heap.feml. This time, the engine could not read the file, or the file did not say those things. Without it, the partition has no definition to be checked against. The engine could fall back on defaults hidden in code, but then you would have two sources of truth. So it refuses. The message names the path and the reason. Check that heap.feml exists, can be read, and states the whole partition. Then start again.
Text from the Rush engine's error catalogue.