Not an error if no hook found in the registry.

Hooks are optional so we shouldn't log an error if one wasn't found.

Thanks Mathias Breiner.

README.txt

@@ -880,7 +880,8 @@ Thanks to Gerald Haider for noticing that installing a service with NSSM in a
 path containing spaces was technically a security vulnerability.
 Thanks to Scott Ware for reporting a crash saving the environment on XP 32-bit.
 Thanks to Stefan and Michael Scherer for reporting a bug writing the event messages source.
-Thanks to Paul Baxter and Mathias Breiner for help with Visual Studio 2015.
+Thanks to Paul Baxter for help with Visual Studio 2015.
+Thanks to Mathias Breiner for help with Visual Studio and some registry fixes.
 
 Licence
 -------

registry.cpp

@@ -822,8 +822,15 @@ int get_hook(const TCHAR *service_name, const TCHAR *hook_event, const TCHAR *ho
     log_event(EVENTLOG_ERROR_TYPE, NSSM_EVENT_OUT_OF_MEMORY, _T("hook registry"), _T("get_hook()"), 0);
     return 1;
   }
-  HKEY key = open_registry(service_name, registry, KEY_READ, false);
-  if (! key) return 1;
+  HKEY key;
+  long error = open_registry(service_name, registry, KEY_READ, &key, false);
+  if (! key) {
+    if (error == ERROR_FILE_NOT_FOUND) {
+      ZeroMemory(buffer, buflen);
+      return 0;
+    }
+    return 1;
+  }
 
   int ret = expand_parameter(key, (TCHAR *) hook_action, buffer, buflen, true, false);