fix: handle undefined projection in setProjection to prevent setState crash (maplibre#7330)

* test: add failing test for setState crash when target style has no projection

setState crashes with "Cannot read properties of undefined (reading 'type')"
when switching from a style with an explicit projection to one without.
The diff() function emits {command: 'setProjection', args: [undefined]},
and setProjection(undefined) dereferences undefined.type.

* fix: skip setProjection in setState style diff

Projection is owned by the map, not the style. setState should not mutate
it as a side effect of diffing two style JSONs. This matches the existing
pattern for setCenter/setZoom/setBearing/setPitch/setRoll, which are also
skipped during style diffs.

* test: update 'do operations if there are changes' test to remove the setProjection spy

and projection assignment, since setState no longer processes projection
diff commands.

* chore: add changelog entry for maplibre#7314

* fix: handle undefined projection in setProjection

When setState diffs a style with a projection field against one without,
diff() emits setProjection(undefined) which crashes on undefined.type.
Default to {type: 'mercator'} when projection is undefined, so
setProjection handles a missing value without crashing.

* fix: preserve original projection value in stylesheet during setProjection

* Apply suggestion from @HarelM

---------

Co-authored-by: Harel M <harel.mazor@gmail.com>

Author: ashwinuae

CHANGELOG.md

@@ -3,9 +3,9 @@
 - _...Add new stuff here..._
 
 ### 🐞 Bug fixes
-- _...Add new stuff here..._
 - Make `fitBounds` and `fitScreenCoordinates` respect the `zoomSnap` map option by snapping the zoom level down to keep bounds fully visible ([#7332](https://github.com/maplibre/maplibre-gl-js/issues/7332) (by [@CommanderStorm](https://github.com/CommanderStorm))
 - Make `jumpTo`, `easeTo`, and `flyTo` respect the `zoomSnap` map option by snapping the zoom level to the nearest valid increment ([#7333](https://github.com/maplibre/maplibre-gl-js/issues/7333) (by [@CommanderStorm](https://github.com/CommanderStorm))
+- Fix `setState` crash when switching styles while globe projection is active ([#7314](https://github.com/maplibre/maplibre-gl-js/issues/7314)) (by [@ashwinuae](https://github.com/ashwinuae))
 
 ## 5.21.1
 

src/style/style.test.ts

@@ -1103,6 +1103,33 @@ describe('Style.setState', () => {
 
         expect(didChange).toBeTruthy();
     });
+
+    test('setState does not crash when target style has no projection', async () => {
+        const style = createStyle();
+        const initialStyle = createStyleJSON({
+            projection: {type: 'globe'}
+        });
+        style.loadJSON(initialStyle);
+        await style.once('style.load');
+
+        const targetStyle = createStyleJSON();
+        expect(() => style.setState(targetStyle)).not.toThrow();
+    });
+
+    test('setState preserves serialized style when target has no projection', async () => {
+        const style = createStyle();
+        const initialStyle = createStyleJSON({
+            projection: {type: 'globe'}
+        });
+        style.loadJSON(initialStyle);
+        await style.once('style.load');
+
+        const targetStyle = createStyleJSON();
+        style.setState(targetStyle);
+
+        const serialized = style.serialize();
+        expect(serialized).not.toHaveProperty('projection');
+    });
 });
 
 describe('Style.addSource', () => {

src/style/style.ts

@@ -1685,15 +1685,16 @@ export class Style extends Evented {
 
     setProjection(projection: ProjectionSpecification) {
         this._checkLoaded();
+        const resolvedProjection = projection ?? {type: 'mercator'};
         this.stylesheet.projection = projection;
         if (this.projection) {
-            if (this.projection.name === projection.type) {
+            if (this.projection.name === resolvedProjection.type) {
                 return;
             }
             this.projection.destroy();
             delete this.projection;
         }
-        this._setProjectionInternal(projection.type);
+        this._setProjectionInternal(resolvedProjection.type);
     }
 
     getSky(): SkySpecification {