Replace panic example with a simpler version

src/error/panic.md

@@ -1,19 +1,19 @@
 # `panic`
 
-The simplest error handling mechanism we will see is `panic`. It prints an 
-error message, starts unwinding the stack, and usually exits the program. 
-Here, we explicitly call `panic` on our error condition: 
+The simplest error handling mechanism we will see is `panic`. It prints an
+error message, starts unwinding the stack, and usually exits the program.
+Here, we explicitly call `panic` on our error condition:
 
 ```rust,editable,ignore,mdbook-runnable
-fn give_princess(gift: &str) {
-    // Princesses hate snakes, so we need to stop if she disapproves!
-    if gift == "snake" { panic!("AAAaaaaa!!!!"); }
+fn drink(beverage: &str) {
+    // You shouldn't drink too much sugary beverages.
+    if beverage == "lemonade" { panic!("AAAaaaaa!!!!"); }
 
-    println!("I love {}s!!!!!", gift);
+    println!("Some refreshing {} is all I need.", beverage);
 }
 
 fn main() {
-    give_princess("teddy bear");
-    give_princess("snake");
+    drink("water");
+    drink("lemonade");
 }
 ```