Changed error to use defined arg

Author: jim-hill-r

src/Neo4jDFG/services/CommonFunctions.jl

@@ -315,8 +315,8 @@ function _matchmergeVariableSubnode!(
         result = commit(tx)
     end
     length(result.errors) > 0 && error(string(result.errors))
-    length(result.results[1]["data"]) != 1 && error("Cannot find subnode '$(ppe.solveKey)' for variable '$variablekey'")
-    length(result.results[1]["data"][1]["row"]) != 1 && error("Cannot find subnode '$(ppe.solveKey)' for variable '$variablekey'")
+    length(result.results[1]["data"]) != 1 && error("Cannot find subnode '$(subnode)' for variable '$variablekey'")
+    length(result.results[1]["data"][1]["row"]) != 1 && error("Cannot find subnode '$(subnode)' for variable '$variablekey'")
     return result.results[1]["data"][1]["row"][1]
 end