fix aborts returning 'missing' data and standardize to AbortSignal

src/reader/repository.ts

@@ -3,7 +3,7 @@
  */
 
 import type { Storage, RequestOptions } from "../storage/storage.js";
-import { NotFoundError, AbortError } from "../storage/storage.js";
+import { NotFoundError, isAbortError } from "../storage/storage.js";
 import {
   getBranchRefDirPath,
   getBranchRefPath,
@@ -63,7 +63,7 @@ export class Repository {
    * @param options - Optional request options (signal for cancellation)
    * @returns ParsedRepo if v2 format, null if v1 format
    * @throws Error if repo file exists but fails to parse
-   * @throws AbortError if the operation was aborted
+   * @throws An error named "AbortError" if the operation was aborted
    */
   private async loadRepoInfo(
     options?: RequestOptions,
@@ -83,7 +83,7 @@ export class Repository {
       return this.repoInfo;
     } catch (error) {
       // Propagate abort errors
-      if (error instanceof AbortError) {
+      if (isAbortError(error)) {
         this.repoInfoAttempted = false; // Allow retry
         throw error;
       }
@@ -167,7 +167,7 @@ export class Repository {
       }
     } catch (error) {
       // Propagate abort errors
-      if (error instanceof AbortError) {
+      if (isAbortError(error)) {
         throw error;
       }
       // Listing not supported - try legacy path only
@@ -208,7 +208,7 @@ export class Repository {
       }
     } catch (error) {
       // Propagate abort errors
-      if (error instanceof AbortError) {
+      if (isAbortError(error)) {
         throw error;
       }
       // Listing not supported - return legacy path without checking exists.
@@ -265,7 +265,7 @@ export class Repository {
         }
       }
     } catch (error) {
-      if (error instanceof AbortError) {
+      if (isAbortError(error)) {
         throw error;
       }
       throw new Error("Cannot list branches: storage does not support listing");
@@ -322,7 +322,7 @@ export class Repository {
         }
       }
     } catch (error) {
-      if (error instanceof AbortError) {
+      if (isAbortError(error)) {
         throw error;
       }
       throw new Error("Cannot list tags: storage does not support listing");

src/reader/session.ts

@@ -3,7 +3,6 @@
  */
 
 import type { Storage, ByteRange, RequestOptions } from "../storage/storage.js";
-import { AbortError } from "../storage/storage.js";
 import { decompress } from "fzstd";
 import { LRUCache } from "../cache/lru.js";
 import {
@@ -307,8 +306,7 @@ export class ReadSession {
     coords: number[],
     options?: RequestOptions,
   ): Promise<Uint8Array | null> {
-    // Early abort check
-    if (options?.signal?.aborted) return null;
+    options?.signal?.throwIfAborted();
 
     const node = this.getNode(path);
     if (!node || node.nodeData.type !== "array") {
@@ -318,28 +316,22 @@ export class ReadSession {
     // Find the manifest that contains this chunk
     const arrayData = node.nodeData;
 
-    try {
-      for (const manifestRef of arrayData.manifests) {
-        // Check if this manifest covers the requested coordinates
-        if (!this.coordsInExtents(coords, manifestRef.extents)) {
-          continue;
-        }
+    for (const manifestRef of arrayData.manifests) {
+      // Check if this manifest covers the requested coordinates
+      if (!this.coordsInExtents(coords, manifestRef.extents)) {
+        continue;
+      }
 
-        // Load the manifest with signal
-        const manifest = await this.loadManifest(manifestRef.objectId, options);
+      // Load the manifest with signal
+      const manifest = await this.loadManifest(manifestRef.objectId, options);
 
-        // Find the chunk reference
-        const chunkRef = findChunkRef(manifest, node.id, coords);
-        if (!chunkRef) continue;
+      // Find the chunk reference
+      const chunkRef = findChunkRef(manifest, node.id, coords);
+      if (!chunkRef) continue;
 
-        // Fetch the chunk data based on payload type with signal
-        const payload = getChunkPayload(chunkRef);
-        return this.fetchChunkPayload(payload, options);
-      }
-    } catch (error) {
-      // Mid-flight abort → return null
-      if (error instanceof AbortError) return null;
-      throw error;
+      // Fetch the chunk data based on payload type with signal
+      const payload = getChunkPayload(chunkRef);
+      return this.fetchChunkPayload(payload, options);
     }
 
     return null;
@@ -364,7 +356,7 @@ export class ReadSession {
     range: { offset: number; length: number } | { suffixLength: number },
     options?: RequestOptions,
   ): Promise<Uint8Array | null> {
-    if (options?.signal?.aborted) return null;
+    options?.signal?.throwIfAborted();
 
     const node = this.getNode(path);
     if (!node || node.nodeData.type !== "array") {
@@ -373,22 +365,17 @@ export class ReadSession {
 
     const arrayData = node.nodeData;
 
-    try {
-      for (const manifestRef of arrayData.manifests) {
-        if (!this.coordsInExtents(coords, manifestRef.extents)) {
-          continue;
-        }
+    for (const manifestRef of arrayData.manifests) {
+      if (!this.coordsInExtents(coords, manifestRef.extents)) {
+        continue;
+      }
 
-        const manifest = await this.loadManifest(manifestRef.objectId, options);
-        const chunkRef = findChunkRef(manifest, node.id, coords);
-        if (!chunkRef) continue;
+      const manifest = await this.loadManifest(manifestRef.objectId, options);
+      const chunkRef = findChunkRef(manifest, node.id, coords);
+      if (!chunkRef) continue;
 
-        const payload = getChunkPayload(chunkRef);
-        return this.fetchChunkPayloadRange(payload, range, options);
-      }
-    } catch (error) {
-      if (error instanceof AbortError) return null;
-      throw error;
+      const payload = getChunkPayload(chunkRef);
+      return this.fetchChunkPayloadRange(payload, range, options);
     }
 
     return null;
@@ -469,19 +456,10 @@ export class ReadSession {
           signal: options?.signal,
         };
 
-        let response: Response;
-        try {
-          const client = options?.fetchClient;
-          response = client
-            ? await client.fetch(httpUrl, fetchInit)
-            : await fetch(httpUrl, fetchInit);
-        } catch (error) {
-          // Translate abort errors to our class (handles DOMException and other implementations)
-          if (error instanceof Error && error.name === "AbortError") {
-            throw new AbortError();
-          }
-          throw error;
-        }
+        const client = options?.fetchClient;
+        const response = client
+          ? await client.fetch(httpUrl, fetchInit)
+          : await fetch(httpUrl, fetchInit);
 
         if (response.status === 412) {
           throw new Error(
@@ -596,18 +574,10 @@ export class ReadSession {
           signal: options?.signal,
         };
 
-        let response: Response;
-        try {
-          const client = options?.fetchClient;
-          response = client
-            ? await client.fetch(httpUrl, fetchInit)
-            : await fetch(httpUrl, fetchInit);
-        } catch (error) {
-          if (error instanceof Error && error.name === "AbortError") {
-            throw new AbortError();
-          }
-          throw error;
-        }
+        const client = options?.fetchClient;
+        const response = client
+          ? await client.fetch(httpUrl, fetchInit)
+          : await fetch(httpUrl, fetchInit);
 
         if (response.status === 412) {
           throw new Error(

src/storage/http-storage.ts

@@ -5,7 +5,7 @@
  */
 
 import type { Storage, ByteRange, RequestOptions } from "./storage.js";
-import { NotFoundError, StorageError, AbortError } from "./storage.js";
+import { NotFoundError, StorageError, isAbortError } from "./storage.js";
 
 /** Options for HTTP storage */
 export interface HttpStorageOptions {
@@ -65,10 +65,7 @@ export class HttpStorage implements Storage {
     range?: ByteRange,
     options?: RequestOptions,
   ): Promise<Uint8Array> {
-    // Early abort check
-    if (options?.signal?.aborted) {
-      throw new AbortError();
-    }
+    options?.signal?.throwIfAborted();
 
     const url = this.getUrl(path);
     const headers = this.getHeaders(range);
@@ -83,10 +80,7 @@ export class HttpStorage implements Storage {
         signal: options?.signal,
       });
     } catch (error) {
-      // Translate abort errors to our class (handles DOMException and other implementations)
-      if (error instanceof Error && error.name === "AbortError") {
-        throw new AbortError();
-      }
+      if (isAbortError(error)) throw error;
       throw new StorageError(
         `Failed to fetch ${url}: ${error instanceof Error ? error.message : String(error)}`,
         error instanceof Error ? error : undefined,
@@ -109,10 +103,7 @@ export class HttpStorage implements Storage {
   }
 
   async exists(path: string, options?: RequestOptions): Promise<boolean> {
-    // Early abort check
-    if (options?.signal?.aborted) {
-      throw new AbortError();
-    }
+    options?.signal?.throwIfAborted();
 
     const url = this.getUrl(path);
 
@@ -126,10 +117,7 @@ export class HttpStorage implements Storage {
 
       return response.ok;
     } catch (error) {
-      // Rethrow abort errors (handles DOMException and other implementations)
-      if (error instanceof Error && error.name === "AbortError") {
-        throw new AbortError();
-      }
+      if (isAbortError(error)) throw error;
       return false;
     }
   }

src/storage/storage.ts

@@ -82,12 +82,17 @@ export class StorageError extends Error {
   }
 }
 
-/** Error thrown when an operation is aborted */
-export class AbortError extends Error {
-  constructor(message = "Operation aborted") {
-    super(message);
-    this.name = "AbortError";
-  }
+type ErrorWithName = { name: unknown };
+
+function hasErrorName(error: unknown): error is ErrorWithName {
+  return typeof error === "object" && error !== null && "name" in error;
+}
+
+/** True for web-platform abort errors from fetch/AbortSignal. */
+export function isAbortError(
+  error: unknown,
+): error is ErrorWithName & { name: "AbortError" } {
+  return hasErrorName(error) && error.name === "AbortError";
 }
 
 /**
@@ -105,7 +110,7 @@ export interface Storage {
    * @returns Object data as bytes
    * @throws NotFoundError if the object doesn't exist
    * @throws StorageError for other errors
-   * @throws AbortError if the operation was aborted
+   * @throws An error named "AbortError" if the operation was aborted
    */
   getObject(
     path: string,
@@ -119,7 +124,7 @@ export interface Storage {
    * @param path - Path to the object
    * @param options - Optional request options (signal for cancellation)
    * @returns True if the object exists
-   * @throws AbortError if the operation was aborted
+   * @throws An error named "AbortError" if the operation was aborted
    */
   exists(path: string, options?: RequestOptions): Promise<boolean>;
 

src/store.ts

@@ -9,6 +9,7 @@ import { Repository } from "./reader/repository.js";
 import { ReadSession } from "./reader/session.js";
 import { HttpStorage } from "./storage/http-storage.js";
 import type { Storage, FetchClient } from "./storage/storage.js";
+import { NotFoundError } from "./storage/storage.js";
 import type { NodeSnapshot } from "./format/flatbuffers/types.js";
 
 /**
@@ -219,7 +220,7 @@ export class IcechunkStore implements AsyncReadable {
     key: AbsolutePath,
     opts?: { signal?: AbortSignal },
   ): Promise<Uint8Array | undefined> {
-    if (opts?.signal?.aborted) return undefined;
+    opts?.signal?.throwIfAborted();
 
     const parsed = parseZarrKey(key);
     const resolvedPath = this.resolvePath(parsed.path);
@@ -237,8 +238,15 @@ export class IcechunkStore implements AsyncReadable {
         azureAccount: this.azureAccount,
       });
       return chunk ?? undefined;
-    } catch {
-      return undefined;
+    } catch (err) {
+      // Only treat "chunk legitimately absent" as undefined. Propagate
+      // everything else — swallowing aborts/network errors here causes
+      // zarrita's Array.getChunk to return a fillValue chunk, which
+      // downstream consumers cache as valid data (e.g. zarr-layer commits
+      // it to region.data, producing permanent blank regions even after
+      // repainting).
+      if (err instanceof NotFoundError) return undefined;
+      throw err;
     }
   }
 
@@ -259,7 +267,7 @@ export class IcechunkStore implements AsyncReadable {
     range: RangeQuery,
     opts?: { signal?: AbortSignal },
   ): Promise<Uint8Array | undefined> {
-    if (opts?.signal?.aborted) return undefined;
+    opts?.signal?.throwIfAborted();
 
     const parsed = parseZarrKey(key);
     const resolvedPath = this.resolvePath(parsed.path);
@@ -289,8 +297,12 @@ export class IcechunkStore implements AsyncReadable {
         return data.slice(-range.suffixLength);
       }
       return data.slice(range.offset, range.offset + range.length);
-    } catch {
-      return undefined;
+    } catch (err) {
+      // Same rationale as `get()`: don't swallow aborts or real errors,
+      // or zarrita will silently fall back to a fillValue chunk and
+      // consumers will cache that garbage as valid data.
+      if (err instanceof NotFoundError) return undefined;
+      throw err;
     }
   }
 

tests/reader/repository.test.ts

@@ -68,6 +68,17 @@ describe("Repository", () => {
       );
     });
 
+    it("should propagate native abort errors while opening", async () => {
+      const abortError = new DOMException("Aborted", "AbortError");
+      const storage = new (class extends MockStorage {
+        async getObject(): Promise<Uint8Array> {
+          throw abortError;
+        }
+      })();
+
+      await expect(Repository.open({ storage })).rejects.toBe(abortError);
+    });
+
     it("should open a valid v1 repository with main branch", async () => {
       const snapshotId = createMockSnapshotId(1);
       const storage = new MockStorage({