From 17d1adedbc5b38b6cb45a08ebed64e099f11534c Mon Sep 17 00:00:00 2001
From: Roman Priesol <roman@priesol.net>
Date: Sat, 12 Sep 2026 13:27:53 +0200
Subject: [PATCH] Guard syncTerrain against running before the style has loaded

---
 public/js/overlays.js | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/public/js/overlays.js b/public/js/overlays.js
index c032f5a..06549ac 100644
--- a/public/js/overlays.js
+++ b/public/js/overlays.js
@@ -100,6 +100,11 @@ class HillshadeControl {
   // showing raised terrain needs both "tilted enough to see it" and "the
   // DEM source this checkbox controls is actually loaded".
   syncTerrain(pitched) {
+    // setLight/setTerrain throw if the style isn't loaded yet — called
+    // synchronously from map.js's setOverlaysControl during page init,
+    // before the first style.load; that listener re-invokes this once it
+    // actually is loaded, so bailing here just skips the premature call.
+    if (!this._map.isStyleLoaded()) return;
     const terrainOn = pitched && this._active && this._map.getSource(HILLSHADE_ID);
     if (terrainOn) {
       this._map.setTerrain({ source: HILLSHADE_ID, exaggeration: 3 });