Potentially uninitialized local pointer variable 'node' used. C++

I am really new to C++ and this code was an example in my book so it should work because I have to implement a few new functions into this. However, I copied the code line for line and I keep getting this error message now my code won't compile until I fix it.

It says that my local pointer 'node' is being used. I don't know what this actually means. Could anyone tell me whats is the error actually telling me? Also could some one help me fix this so I can start my project? I'm only asking for the code because this isn't part of my project, it was already given by the teacher.

Here is my code:

// ListNode.h
#ifndef _LISTNODE_H
#define _LISTNODE_H

#include <cstdlib>

typedef int ItemType;

class ListNode {
    friend class LList;

public:
    ListNode(ItemType item, ListNode* link = NULL);

private:
    ItemType item_;
    ListNode *link_;
};

inline ListNode::ListNode(ItemType item, ListNode *link)
{
    item_ = item;
    link_ = link;
}

#endif // _LISTNODE_H

// LList.h
#ifndef _LLIST_H
#define _LLIST_H

#include "ListNode.h"

class LList {

public:
    LList();
    LList(const LList& source);
    ~LList();

    LList& operator=(const LList& source);
    int size() { return size_; }
    void append(ItemType x);
    void insert(size_t i, ItemType x);
    ItemType pop(int i = -1);
    ItemType& operator[](size_t position);

private:
    // methods
    void copy(const LList &source);
    void dealloc();
    ListNode* _find(size_t position);
    ItemType _delete(size_t position);

    // data elements
    ListNode *head_;
    int size_;
};

#endif // _LLIST_H

// LList.cpp
#include "LList.h"

LList::LList()
{
    head_ = NULL;
    size_ = 0;
}

ListNode* LList::_find(size_t position)
{
    ListNode *node = head_;
    size_t i;

    for (i = 0; i<position; i++) {
        node = node->link_;
    }
    return node;
}

ItemType LList::_delete(size_t position)
{
    ListNode *node, *dnode;
    ItemType item;

    if (position == 0) {
        dnode = head_;
        head_ = head_->link_;
        item = dnode->item_;
        delete dnode;
    }
    else {
        node = _find(position - 1);
        if (node != NULL) {
            dnode = node->link_;
            node->link_ = dnode->link_;
            item = dnode->item_;
            delete dnode;
        }
    }
    size_ -= 1;
    return item;
}

void LList::append(ItemType x)
{
    ListNode *node, *newNode = new ListNode(x);

    if (head_ != NULL) {
        node = _find(size_ - 1);
        node->link_ = newNode;
    }
    else {
        head_ = newNode;
    }
    size_ += 1;
}

void LList::insert(size_t i, ItemType x)
{
    ListNode *node;

    if (i == 0) {
        head_ = new ListNode(x, head_);
    }
    else {
        node = _find(i - 1);
        node->link_ = new ListNode(x, node->link_);
    }
    size_ += 1;
}

ItemType LList::pop(int i)
{
    if (i == -1) {
        i = size_ - 1;
    }
    return _delete(i);
}

ItemType& LList::operator[](size_t position)
{
    ListNode *node;

    node = _find(position);
    return node->item_;
}

LList::LList(const LList& source)
{
    copy(source);
}

void LList::copy(const LList &source)
{
    ListNode *snode, *node;

    snode = source.head_;
    if (snode) {
        node = head_ = new ListNode(snode->item_);
        snode = snode->link_;
    }
    while (snode) {
        node->link_ = new ListNode(snode->item_);
        node = node->link_;
        snode = snode->link_;
    }
    size_ = source.size_;
}

LList& LList::operator=(const LList& source)
{
    if (this != &source) {
        dealloc();
        copy(source);
    }
    return *this;
}

LList::~LList()
{
    dealloc();
}

void LList::dealloc()
{
    ListNode *node, *dnode;

    node = head_;
    while (node) {
        dnode = node;
        node = node->link_;
        delete dnode;
    }
}

I know where the problem is exactly (Line 104 in my code)

node->link_ = new ListNode(snode->item_);

This part of my code is the problem. Could anyone help me fix this problem so I can work on my program? Thanks!

Now that my previous problem was answered I have a new one.

How would I go about testing my code? I have a few lines but it keeps coming out with errors when I try to print out the contents of my LList. This is my test code:

#include "LList.h"

int main()
{
    LList b, c;
    int x;

    b.append(1);
    b.append(2);
    b.append(3);
    c.append(4);
    c.append(5);
    c = b;
    x = b.pop();
} 

Could anyone help me write a working test code, this the last thing I will need to start adding my different functions.