Fix nil panic in UpdateCache when listapisresponse is empty (#211) (#217)

* Fix nil panic in UpdateCache when listapisresponse is empty (#211)

* Keep existing API cache when listApis returns an empty response

Move the nil guard above the cache reset so a failed sync no longer
clears the in-memory API cache, and return 0 so 'cmk sync' prints
"Discovered 0 APIs" instead of "Discovered <nil> APIs".

---------

Co-authored-by: Boris Stoyanov <bss.stoyanov@gmail.com>

Author: rohanmishra29

config/cache.go

@@ -108,6 +108,11 @@ func (c *Config) SaveCache(response map[string]interface{}) {
 
 // UpdateCache uses auto-discovery data to update internal API cache
 func (c *Config) UpdateCache(response map[string]interface{}) interface{} {
+	if response["api"] == nil {
+		fmt.Fprintf(os.Stderr, "Error: empty API list received, sync failed. Existing API cache is kept.\n")
+		return 0
+	}
+
 	apiCache = make(map[string]*API)
 	apiVerbMap = nil