Handle empty MLT tiles the same as MVT

js/src/adapters.ts

@@ -33,9 +33,12 @@ export const leafletRasterLayer = (source: PMTiles, options: unknown) => {
       };
       if (!loaded) {
         source.getHeader().then((header) => {
-          if (header.tileType === TileType.Mvt) {
+          if (
+            header.tileType === TileType.Mvt ||
+            header.tileType === TileType.Mlt
+          ) {
             console.error(
-              "Error: archive contains MVT vector tiles, but leafletRasterLayer is for displaying raster tiles. See https://github.com/protomaps/PMTiles/tree/main/js for details."
+              "Error: archive contains vector tiles, but leafletRasterLayer is for displaying raster tiles. See https://github.com/protomaps/PMTiles/tree/main/js for details."
             );
           } else if (header.tileType === 2) {
             mimeType = "image/png";
@@ -267,7 +270,7 @@ export class Protocol {
       };
     }
     const header = await instance.getHeader();
-    if (header.tileType === TileType.Mvt) {
+    if (header.tileType === TileType.Mvt || header.tileType === TileType.Mlt) {
       if (this.errorOnMissingTile) {
         throw new Error("Tile not found.");
       }

js/test/adapter.test.ts

@@ -44,7 +44,7 @@ describe("Protocol", () => {
     assert.strictEqual(result.data.length, 49);
   });
 
-  test("returns empty data for missing tile if errorOnMissingTile is false", async () => {
+  test("returns empty data for missing MVT tile if errorOnMissingTile is false", async () => {
     const pmtiles = new PMTiles("http://localhost:1337/example.pmtiles");
     const protocol = new Protocol({ errorOnMissingTile: false });
     protocol.add(pmtiles);
@@ -61,7 +61,7 @@ describe("Protocol", () => {
     assert.strictEqual(result.data.length, 0);
   });
 
-  test("throws error for missing tile if errorOnMissingTile is true", async () => {
+  test("throws error for missing MVT tile if errorOnMissingTile is true", async () => {
     const pmtiles = new PMTiles("http://localhost:1337/example.pmtiles");
     const protocol = new Protocol({ errorOnMissingTile: true });
     protocol.add(pmtiles);
@@ -77,6 +77,39 @@ describe("Protocol", () => {
     assert.rejects(promise, { message: "Tile not found." });
   });
 
+  test("returns empty data for missing MLT tile if errorOnMissingTile is false", async () => {
+    const pmtiles = new PMTiles("http://localhost:1337/mlt.pmtiles");
+    const protocol = new Protocol({ errorOnMissingTile: false });
+    protocol.add(pmtiles);
+
+    const result = await protocol.tilev4(
+      {
+        url: "pmtiles://http://localhost:1337/mlt.pmtiles/25/0/0",
+        type: "arrayBuffer",
+      },
+      new AbortController()
+    );
+
+    assert.ok(result.data instanceof Uint8Array);
+    assert.strictEqual(result.data.length, 0);
+  });
+
+  test("throws error for missing MLT tile if errorOnMissingTile is true", async () => {
+    const pmtiles = new PMTiles("http://localhost:1337/mlt.pmtiles");
+    const protocol = new Protocol({ errorOnMissingTile: true });
+    protocol.add(pmtiles);
+
+    const promise = protocol.tilev4(
+      {
+        url: "pmtiles://http://localhost:1337/mlt.pmtiles/25/0/0",
+        type: "arrayBuffer",
+      },
+      new AbortController()
+    );
+
+    assert.rejects(promise, { message: "Tile not found." });
+  });
+
   test("throws AbortError when AbortController is signaled while accessing TileJSON", async () => {
     const pmtiles = new PMTiles("http://localhost:1337/example.pmtiles");
     const protocol = new Protocol();

js/test/utils.ts

@@ -20,6 +20,9 @@ class MockServer {
     this.etag = undefined;
     this.lastRequestHeaders = null;
     const serverBuffer = fs.readFileSync("test/data/test_fixture_1.pmtiles");
+    const serverBufferMlt = fs.readFileSync(
+      "test/data/test_fixture_mlt.pmtiles"
+    );
     const server = setupServer(
       http.get(
         "http://localhost:1337/example.pmtiles",
@@ -65,6 +68,24 @@ class MockServer {
           status: 206,
           headers: { etag: this.etag } as HeadersInit,
         });
+      }),
+      http.get("http://localhost:1337/mlt.pmtiles", ({ request, params }) => {
+        this.lastCache = request.cache;
+        this.lastRequestHeaders = request.headers;
+        this.lastCredentials = request.credentials;
+        this.numRequests++;
+        const range = request.headers.get("range")?.substr(6).split("-");
+        if (!range) {
+          throw new Error("invalid range");
+        }
+        const offset = +range[0];
+        const length = +range[1];
+        const body = serverBufferMlt.slice(offset, offset + length - 1);
+        return new HttpResponse(body, {
+          status: 206,
+          statusText: "OK",
+          headers: { etag: this.etag } as HeadersInit,
+        });
       })
     );
     server.listen({ onUnhandledRequest: "error" });