show error when specified map provider is not current provider when using map image proxy

pkg/api/map_image_proxies.go

@@ -32,6 +32,10 @@ func (p *MapImageProxy) MapTileImageProxyHandler(c *core.Context) (*httputil.Rev
 	mapProvider := strings.Replace(c.Query("provider"), "-", "_", -1)
 	targetUrl := ""
 
+	if mapProvider != settings.Container.Current.MapProvider {
+		return nil, errs.ErrMapProviderNotCurrent
+	}
+
 	if mapProvider == settings.OpenStreetMapProvider {
 		targetUrl = openStreetMapTileImageUrlFormat
 	} else if mapProvider == settings.OpenStreetMapHumanitarianStyleProvider {

pkg/errs/error.go

@@ -28,6 +28,7 @@ const (
 	NormalSubcategoryCategory       = 6
 	NormalSubcategoryTag            = 7
 	NormalSubcategoryDataManagement = 8
+	NormalSubcategoryMapProxy       = 9
 )
 
 // Error represents the specific error returned to user

pkg/errs/map_image_proxy.go

@@ -0,0 +1,8 @@
+package errs
+
+import "net/http"
+
+// Error codes related to map image proxy
+var (
+	ErrMapProviderNotCurrent = NewNormalError(NormalSubcategoryMapProxy, 0, http.StatusBadRequest, "specified map provider is not set")
+)