Segmentation fault when storing top of stack into structure

Question

I'm trying to implement a undo/redo function in a super simple text editor, as a project. I have a class, CommandProcessor, that takes what buttons the user pressed, and if it matches, executes a generic command that calls an execute() function of the type of object that uses that specific command, ie.

struct UserInteraction
{
    UserInteractionType type; // this is just a enum type
    Command* command;
};

case 'U':
    command = new MoveLeft;
    return makeCommandInteraction(command);

Here is the MoveLeft command it calls:

void MoveLeft::execute(Editor& editor)
{
    // if we try to move past the amount of input, throw exception
    if(editor.cursorColumn() == 1) {
        throw EditorException("Already at beginning!");
    } else { // otherwise, move the cursor left
        editor.moveCursorLeft();
    }
}

And within that, here is the Editor command that gets called.

void Editor::moveCursorLeft()
{
    column--;
}

If the user hits ctrl + z, or ctrl + a, we return a undo/redo command: return makeUndoInteraction(); or return makeRedoInteraction();

I'm using two stacks, one for undo, and one for redo. undoStack stores the latest command and when called in the processor, calls an undo function (which currently just moves the cursor to the right) from MoveLeft, pushes the top of the undoStack to redoStack, and then pops the top of undoStack. redoStack holds the last undo command, and therefore, I store it in interaction which is the type that holds the commands. With this, I call execute() from MoveLeft, and then push the interaction back onto undoStack Here are both functions:

 else if (interaction.type == UserInteractionType::undo)
        {
            try
            {
                interaction.command->undo(editor);
                redoStack.push(undoStack.top());
                undoStack.pop();
                view.clearErrorMessage();
            } catch (EditorException& e)
            {
                view.showErrorMessage(e.getReason());
            }
            view.refresh();
            delete interaction.command; // delete command since we stored it in the stack
        }
        else if (interaction.type == UserInteractionType::redo)
        {
            try
            {
                interaction = redoStack.top();
                interaction.command->execute(editor);
                undoStack.push(interaction);
                view.clearErrorMessage();
            }
            catch (EditorException& e)
            {
                view.showErrorMessage(e.getReason());
            }
            view.refresh();
        }

Right now I'm getting "Segmentation fault (core dumped)" at this line in undo:

interaction.command->undo(editor);

And if I just test redo, I get a segmentation fault at this line:

interaction = redoStack.top();

Both are the first line after the try statement. What could be causing it?