fix "cscli" without arguments (#1406)

cmd/crowdsec-cli/main.go

@@ -153,7 +153,7 @@ It is meant to allow you to manage bans, parsers/scenarios/etc, api and generall
 		log.Fatalf("failed to make branch hidden : %s", err)
 	}
 
-	if os.Args[1] != "completion" {
+	if len(os.Args) > 1 && os.Args[1] != "completion" {
 		cobra.OnInitialize(initConfig)
 	}
 

tests/bats/01_base.bats

@@ -26,6 +26,13 @@ declare stderr
 
 #----------
 
+@test "$FILE cscli - usage" {
+    run -0 cscli
+    assert_output --partial "Usage:"
+    assert_output --partial "cscli [command]"
+    assert_output --partial "Available Commands:"
+}
+
 @test "$FILE cscli version" {
     run -0 cscli version
     assert_output --partial "version:"