Fixed bug am42307 (nvault_open did not return -1 on failure)

plugins/testsuite/nvault_test.sma

@@ -0,0 +1,20 @@
+#include <amxmodx>
+#include <nvault>
+
+public plugin_init()
+{
+	register_plugin("nVault Test", "1.0", "BAILOPAN")
+	
+	register_srvcmd("test_nvault", "Command_TestNvault")
+}
+
+public Command_TestNvault()
+{
+	new v = nvault_open("://:/1/R!?#@41345$%:$")
+	server_print("Vault value: %d (expected: %d)", v, -1)
+	
+	if (v != -1)
+	{
+		nvault_close(v)
+	}
+}