Fix undefined key error message

index.js

@@ -15,6 +15,7 @@ const loadModules = require("./load-modules");
 // FIXME: $getProperty, $getPropertyPath, maybe $resolveObject/$query?
 // FIXME: Allow setting an evaluation depth limit for queries, to limit eg. recursion
 // FIXME: recurseDepth, recurseLabel/recurseGoto
+// TODO: Internal queries, but only in modules, and only as a last resort
 
 /* Process design:
 
@@ -154,7 +155,7 @@ function makeEnvironment(context, getContextForModule) {
 				assignErrorPath(error, cursor);
 			});
 		} else {
-			throw new Error(`No key '${schemaKey}' exists in the schema`);
+			throw new Error(`No key '${cursor.schemaPath.at(-1)}' exists in the schema`);
 		}
 	}