fix index oob segfaults

main.c

@@ -235,12 +235,22 @@ void add_command_handler(int width, int height) {
 }
 
 void view_command_handler(int width, int height, int index) {
+  // check if the index is out of bounds
+  if (index < 0 || index >= arrlen(todos)) {
+    return;
+  }
+
   TodoItem item = todos[index];
   // create an alert in the middle of the screen
   alert(item.title, width, height);
 }
 
 void mark_command_handler(int index) {
+  // check if the index is out of bounds
+  if (index < 0 || index >= arrlen(todos)) {
+    return;
+  }
+
   TodoItem item = todos[index];
 
   todo_mark_item(&item, !item.completed);
@@ -252,6 +262,11 @@ void mark_command_handler(int index) {
 }
 
 void remove_command_handler(int index) {
+  // check if the index is out of bounds
+  if (index < 0 || index >= arrlen(todos)) {
+    return;
+  }
+
   arrdel(todos, index);
 
   // set the dirty flag