fix: gitlab empty response (#4152)

Signed-off-by: Gergely Brautigam <182850+Skarlso@users.noreply.github.com>

pkg/provider/gitlab/gitlab.go

@@ -224,14 +224,22 @@ func (g *gitlabBase) GetSecret(_ context.Context, ref esv1beta1.ExternalSecretDa
 
 	data, resp, err := g.projectVariablesClient.GetVariable(g.store.ProjectID, ref.Key, vopts)
 	metrics.ObserveAPICall(constants.ProviderGitLab, constants.CallGitLabProjectVariableGet, err)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp == nil {
+		return nil, errors.New("gitlab response is nil")
+	}
+
 	if !isEmptyOrWildcard(g.store.Environment) && resp.StatusCode == http.StatusNotFound {
 		vopts.Filter.EnvironmentScope = "*"
 		data, resp, err = g.projectVariablesClient.GetVariable(g.store.ProjectID, ref.Key, vopts)
 		metrics.ObserveAPICall(constants.ProviderGitLab, constants.CallGitLabProjectVariableGet, err)
 	}
 
-	if resp.StatusCode >= 400 && resp.StatusCode != http.StatusNotFound && err != nil {
-		return nil, err
+	if resp.StatusCode >= 400 && resp.StatusCode != http.StatusNotFound {
+		return nil, fmt.Errorf("gitlab response status code was not OK: %d", resp.StatusCode)
 	}
 
 	err = g.ResolveGroupIds()