Differences between Insert & Delete for singly linked lists with sentinel nodes - singly-linked-list

Question

We were assigned with the task of coding the Insert(L,k) & Delete(L,k) functions for a singly-linked list with a sentinel node. My questions are:
Is it correct or close to the right answer?
assuming what i've done is correct, i'm not
seeing any significant difference from a normal Delete() of a singly
linked list without a sentinel node. Am i correct in that statement?
Description of Insert(L,k):
The function inserts a new node with key == k in the list (if it doesn't already exist).
Description of Delete(L,k):
The function looks for the node whose key == k and if it finds it, it deletes it.
We can assume that the key of each node is unique.
My implementation of Insert:
fun Insert(pointer L,Key k) {
pointer p;
pointer currNode = L; // first element
while(currNode != NULL && currNode->data != k) {
currNode = currNode->next;
}
if(currNode == NULL) { // element doesn't exist
p = newcell(Node); // allocate memory for a new node
p->data = k;
p->next = L;
L = p;
return;
}
else { // element exists
throw error;
}
}
My implementation of Delete:
fun Delete(pointer L, Key k) {
pointer currNode = L; //first element
pointer prev = NULL; // A pointer to the previous node
if(currNode != NULL && currNode->data == k) { // first elemenent has k
L = currNode->next;
free(currNode);
}
// look for the elemenent to delete
while(currNode->next != NULL && currNode->data != k) {
prev = currNode;
currNode = currNode->next;
}
if(currNode->next == NULL) throw error; // element not found
// elemenent found
prev->next = currNode->next;
free(currNode);
}
P.S. Here's how a singly linked list with a sentinel node looks like in our examples