refactor: extract #fetchChunk, replace Promise.allSettled with self-describing results

src/entities/Font/model/store/appliedFontsStore/appliedFontsStore.svelte.ts

@@ -191,34 +191,7 @@ export class AppliedFontsManager {
         // ==================== PHASE 1: Concurrent Fetching ====================
         // Fetch multiple font files in parallel since network I/O is non-blocking
         for (let i = 0; i < entries.length; i += concurrency) {
-            // Process in chunks based on concurrency limit
+            await this.#fetchChunk(entries.slice(i, i + concurrency), buffers);
-            const chunk = entries.slice(i, i + concurrency);
-            const results = await Promise.allSettled(
-                chunk.map(async ([key, config]) => {
-                    this.statuses.set(key, 'loading');
-                    // Fetch buffer via cache (checks memory → Cache API → network)
-                    const buffer = await this.#cache.get(config.url, this.#abortController.signal);
-                    buffers.set(key, buffer);
-                }),
-            );
-
-            // Handle fetch errors - set status and increment retry count
-            for (let j = 0; j < results.length; j++) {
-                if (results[j].status === 'rejected') {
-                    const [key, config] = chunk[j];
-                    const reason = (results[j] as PromiseRejectedResult).reason;
-                    // Aborted fetches are not retriable failures — skip silently
-                    const isAbort = reason instanceof FontFetchError
-                        && reason.cause instanceof Error
-                        && reason.cause.name === 'AbortError';
-                    if (isAbort) continue;
-                    if (reason instanceof FontFetchError) {
-                        console.error(`Font fetch failed: ${config.name}`, reason);
-                    }
-                    this.statuses.set(key, 'error');
-                    this.#queue.incrementRetry(key);
-                }
-            }
         }
 
         // ==================== PHASE 2: Sequential Parsing ====================
@@ -250,6 +223,43 @@ export class AppliedFontsManager {
         }
     }
 
+    /**
+     * Fetches a chunk of fonts concurrently and populates `buffers` with successful results.
+     * Each promise carries its own key and config so results need no index correlation.
+     * Aborted fetches are silently skipped; other errors set status to `'error'` and increment retry.
+     */
+    async #fetchChunk(
+        chunk: Array<[string, FontLoadRequestConfig]>,
+        buffers: Map<string, ArrayBuffer>,
+    ): Promise<void> {
+        const results = await Promise.all(
+            chunk.map(async ([key, config]) => {
+                this.statuses.set(key, 'loading');
+                try {
+                    const buffer = await this.#cache.get(config.url, this.#abortController.signal);
+                    buffers.set(key, buffer);
+                    return { ok: true as const, key };
+                } catch (reason) {
+                    return { ok: false as const, key, config, reason };
+                }
+            }),
+        );
+
+        for (const result of results) {
+            if (result.ok) continue;
+            const { key, config, reason } = result;
+            const isAbort = reason instanceof FontFetchError
+                && reason.cause instanceof Error
+                && reason.cause.name === 'AbortError';
+            if (isAbort) continue;
+            if (reason instanceof FontFetchError) {
+                console.error(`Font fetch failed: ${config.name}`, reason);
+            }
+            this.statuses.set(key, 'error');
+            this.#queue.incrementRetry(key);
+        }
+    }
+
     /**
      * Parses a fetched buffer into a {@link FontFace}, registers it with `document.fonts`,
      * and updates reactive status. On failure, sets status to `'error'` and increments the retry count.