tweaked get parameter

src/symbol_table.c

@@ -515,6 +515,11 @@ TableNode *getParameter(TableNode *definition) {
             "function. Invalid.");
         return undefined;
     }
+    if(definition->additionalinfo == NULL){
+        printdebug(
+            "node has NULL additionalinfo. Invalid.");
+        return undefined;
+    }
     if (strcmp(getType(definition), "primitive function type") != 0) {
         printdebug(
             "not checking the parameter of a function -- invalid op");