chore(middleware-flexible-checksums): move inline class NodeCrc32 outside

Author: trivikr

packages/middleware-flexible-checksums/src/getCrc32ChecksumAlgorithmFunction.ts

@@ -3,26 +3,28 @@ import { numToUint8 } from "@aws-crypto/util";
 import { Checksum } from "@smithy/types";
 import * as zlib from "zlib";
 
+class NodeCrc32 implements Checksum {
+  checksum = 0;
+
+  update(data: Uint8Array) {
+    // @ts-expect-error crc32 is defined only for Node.js >=v20.15.0 and >=v22.2.0.
+    this.checksum = zlib.crc32(data, this.checksum);
+  }
+
+  async digest() {
+    return numToUint8(this.checksum);
+  }
+
+  reset() {
+    this.checksum = 0;
+  }
+}
+
 export const getCrc32ChecksumAlgorithmFunction = () => {
   // @ts-expect-error crc32 is defined only for Node.js >=v20.15.0 and >=v22.2.0.
   if (typeof zlib.crc32 === "undefined") {
     return AwsCrc32;
   }
 
-  return class NodeCrc32 implements Checksum {
-    checksum = 0;
-
-    update(data: Uint8Array) {
-      // @ts-expect-error crc32 is defined only for Node.js >=v20.15.0 and >=v22.2.0.
-      this.checksum = zlib.crc32(data, this.checksum);
-    }
-
-    async digest() {
-      return numToUint8(this.checksum);
-    }
-
-    reset() {
-      this.checksum = 0;
-    }
-  };
+  return NodeCrc32;
 };