refactor: remove unused func/var/methods (#315)

Signed-off-by: Dhruv Jain <92215138+jaydee029@users.noreply.github.com>

pkg/gateway/error.go

@@ -1,29 +0,0 @@
-package gateway
-
-import (
-	"context"
-	"net/http"
-
-	"github.com/grpc-ecosystem/grpc-gateway/runtime"
-	"github.com/segmentio/encoding/json"
-	"google.golang.org/grpc"
-)
-
-type errorBody struct {
-	Err string `json:"error,omitempty"`
-}
-
-// customErrorHandler implements custom grpc error handler
-func customErrorHandler(ctx context.Context, _ *runtime.ServeMux, marshaler runtime.Marshaler, w http.ResponseWriter, _ *http.Request, err error) {
-	const fallback = `{"error": "failed to marshal error message"}`
-
-	w.Header().Set("Content-type", marshaler.ContentType())
-	w.WriteHeader(runtime.HTTPStatusFromCode(grpc.Code(err)))
-	jErr := json.NewEncoder(w).Encode(errorBody{
-		Err: grpc.ErrorDesc(err),
-	})
-
-	if jErr != nil {
-		w.Write([]byte(fallback))
-	}
-}