add error handling for service not found

server.py

@@ -91,23 +91,27 @@ async def register_service(name: str, ip: str):
 async def read_service(name: str):
     """Reads the hosts file, produces a service catalog entry."""
     catalog = {}
-
-    with open(HOSTS_FILE, "r") as fd:
-        hosts_file = fd.read().split("\n")
-        entries = [
-            entry for entry in hosts_file if not entry.startswith("#") and entry != "\n"
-        ]
-        for entry in entries:
-            match = re.match(r"\s*(\d+\.\d+\.\d+\.\d+)\s+(.+)", entry)
-            if match:
-                ip_address = match.group(1)
-                hostnames = match.group(2).split()
-                for hostname in hostnames:
-                    if hostname not in catalog:
-                        catalog[hostname] = [ip_address]
-                    else:
-                        catalog[hostname].append(ip_address)
-    return catalog[name]
+    try:
+        with open(HOSTS_FILE, "r") as fd:
+            hosts_file = fd.read().split("\n")
+            entries = [
+                entry
+                for entry in hosts_file
+                if not entry.startswith("#") and entry != "\n"
+            ]
+            for entry in entries:
+                match = re.match(r"\s*(\d+\.\d+\.\d+\.\d+)\s+(.+)", entry)
+                if match:
+                    ip_address = match.group(1)
+                    hostnames = match.group(2).split()
+                    for hostname in hostnames:
+                        if hostname not in catalog:
+                            catalog[hostname] = [ip_address]
+                        else:
+                            catalog[hostname].append(ip_address)
+        return catalog[name]
+    except KeyError:
+        raise HTTPException(status_code=404, detail=f"Service not found: {name}")
 
 
 @app.get("/services")