chore(errors1): use `is_empty()` instead of `len() > 0`

more idiomatic according to clippy

exercises/error_handling/errors1.rs

@@ -8,11 +8,11 @@
 // I AM NOT DONE
 
 pub fn generate_nametag_text(name: String) -> Option<String> {
-    if name.len() > 0 {
+    if name.is_empty() {
-        Some(format!("Hi! My name is {}", name))
-    } else {
         // Empty names aren't allowed.
         None
+    } else {
+        Some(format!("Hi! My name is {}", name))
     }
 }