runtime-rs: report error on missing or empty fields in configuration

Removed the setting of default values for runtime fields. Added explicit checks for missing or empty fields, reporting errors with clear messages.

Fixes: #8838

Signed-off-by: yaoyinnan <35447132+yaoyinnan@users.noreply.github.com>

src/libs/kata-types/src/annotations/mod.rs

@@ -12,9 +12,6 @@ use std::u32;
 
 use serde::Deserialize;
 
-use crate::config::default::DEFAULT_AGENT_TYPE_NAME;
-use crate::config::default::DEFAULT_HYPERVISOR;
-use crate::config::default::DEFAULT_RUNTIME_NAME;
 use crate::config::hypervisor::{get_hypervisor_plugin, HugePageType};
 
 use crate::config::TomlConfig;
@@ -463,13 +460,22 @@ impl Annotation {
 
         // set default values for runtime.name, runtime.hypervisor_name and runtime.agent
         if config.runtime.name.is_empty() {
-            config.runtime.name = DEFAULT_RUNTIME_NAME.to_string()
+            return Err(io::Error::new(
+                io::ErrorKind::InvalidData,
+                "Runtime name is missing in the configuration",
+            ));
         }
         if config.runtime.hypervisor_name.is_empty() {
-            config.runtime.hypervisor_name = DEFAULT_HYPERVISOR.to_string()
+            return Err(io::Error::new(
+                io::ErrorKind::InvalidData,
+                "Hypervisor name is missing in the configuration",
+            ));
         }
         if config.runtime.agent_name.is_empty() {
-            config.runtime.agent_name = DEFAULT_AGENT_TYPE_NAME.to_string()
+            return Err(io::Error::new(
+                io::ErrorKind::InvalidData,
+                "Agent name is missing in the configuration",
+            ));
         }
 
         let hypervisor_name = &config.runtime.hypervisor_name;