fix(config): reject empty reflector host entries

src/settings/validation.rs

@@ -213,6 +213,12 @@ impl ReflectorSettings {
         }
 
         for (index, reflector) in self.entries.iter().enumerate() {
+            if reflector.host.trim().is_empty() {
+                report.error(
+                    "reflectors.entries",
+                    format!("entry {index} must have a nonempty host"),
+                );
+            }
             if reflector.protocols.is_empty() {
                 report.error(
                     "reflectors.entries",