Allow some exceptions to be handled

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

@@ -1,5 +1,8 @@
 package carpet.script.exception;
 
+import carpet.script.Context;
+import carpet.script.Expression;
+import carpet.script.Tokenizer;
 import carpet.script.value.FunctionValue;
 
 import java.util.ArrayList;
@@ -13,4 +16,20 @@ public class InternalExpressionException extends RuntimeException
     {
         super(message);
     }
+    
+    /**
+     * <p>Promotes this simple exception into one with context and extra information.
+     * 
+     * <p>Provides a cleaner way of handling similar exceptions, in this case
+     * {@link InternalExpressionException} and {@link ThrowStatement} 
+     * @param c Context
+     * @param e Expression
+     * @param token Token
+     * @return The new {@link ExpressionException} (or {@link ProcessedThrowStatement}),
+     *         depending on the implementation.
+     */
+    public ExpressionException promote(Context c, Expression e, Tokenizer.Token token)
+    {
+        return new ExpressionException(c, e, token, getMessage(), stack);
+    }
 }