imports and better error reporting and stacktraces

src/main/java/carpet/script/exception/InternalExpressionException.java

@@ -1,8 +1,14 @@
 package carpet.script.exception;
 
+import carpet.script.value.FunctionValue;
+
+import java.util.ArrayList;
+import java.util.List;
+
 /* The internal expression evaluators exception class. */
-public class InternalExpressionException extends ExpressionException
+public class InternalExpressionException extends RuntimeException
 {
+    public List<FunctionValue> stack = new ArrayList<>();
     public InternalExpressionException(String message)
     {
         super(message);