[SPARK-52678] Update ArrowReader.swift with GH-54

### What changes were proposed in this pull request?

This PR aims to update `ArrowReader.swift` with `GH-54`.

Please note that we cannot use `Apache Arrow Swift` directly yet because
- It is still unable to support `Decimal`.
  - apache/arrow#46628
- It still uses `GRPC Swift` while we use `GRPC Swift 2`.

### Why are the changes needed?

To be ready for the upstream release because `v21.0.0-rc0` tag is created.
- https://github.com/apache/arrow-swift/releases/tag/v21.0.0-rc0

According to the release notes, this seems to be the only one which needs to catch up.

### Does this PR introduce _any_ user-facing change?

No behavior change because this is a refactoring to suppress warning messages.

### How was this patch tested?

Pass the CIs.

### Was this patch authored or co-authored using generative AI tooling?

No.

Closes #207 from dongjoon-hyun/SPARK-52678.

Authored-by: Dongjoon Hyun <[email protected]>
Signed-off-by: Dongjoon Hyun <[email protected]>

Author: dongjoon-hyun

Sources/SparkConnect/ArrowReader.swift

@@ -274,23 +274,22 @@ public class ArrowReader {  // swiftlint:disable:this type_body_length
       let message = org_apache_arrow_flatbuf_Message.getRootAsMessage(bb: dataBuffer)
       switch message.headerType {
       case .recordbatch:
-        do {
-          let rbMessage = message.header(type: org_apache_arrow_flatbuf_RecordBatch.self)!
-          let recordBatch = try loadRecordBatch(
-            rbMessage,
-            schema: schemaMessage!,
-            arrowSchema: result.schema!,
-            data: input,
-            messageEndOffset: (Int64(offset) + Int64(length))
-          ).get()
+        let rbMessage = message.header(type: org_apache_arrow_flatbuf_RecordBatch.self)!
+        let recordBatchResult = try loadRecordBatch(
+          rbMessage,
+          schema: schemaMessage!,
+          arrowSchema: result.schema!,
+          data: input,
+          messageEndOffset: (Int64(offset) + Int64(length))
+        )
+        switch recordBatchResult {
+        case .success(let recordBatch):
           result.batches.append(recordBatch)
-          offset += Int(message.bodyLength + Int64(length))
-          length = getUInt32(input, offset: offset)
-        } catch let error as ArrowError {
+        case .failure(let error):
           return .failure(error)
-        } catch {
-          return .failure(.unknownError("Unexpected error: \(error)"))
         }
+        offset += Int(message.bodyLength + Int64(length))
+        length = getUInt32(input, offset: offset)
       case .schema:
         schemaMessage = message.header(type: org_apache_arrow_flatbuf_Schema.self)!
         let schemaResult = loadSchema(schemaMessage!)
@@ -363,20 +362,19 @@ public class ArrowReader {  // swiftlint:disable:this type_body_length
       let message = org_apache_arrow_flatbuf_Message.getRootAsMessage(bb: mbb)
       switch message.headerType {
       case .recordbatch:
-        do {
-          let rbMessage = message.header(type: org_apache_arrow_flatbuf_RecordBatch.self)!
-          let recordBatch = try loadRecordBatch(
-            rbMessage,
-            schema: footer.schema!,
-            arrowSchema: result.schema!,
-            data: fileData,
-            messageEndOffset: messageEndOffset
-          ).get()
+        let rbMessage = message.header(type: org_apache_arrow_flatbuf_RecordBatch.self)!
+        let recordBatchResult = try loadRecordBatch(
+          rbMessage,
+          schema: footer.schema!,
+          arrowSchema: result.schema!,
+          data: fileData,
+          messageEndOffset: messageEndOffset
+        )
+        switch recordBatchResult {
+        case .success(let recordBatch):
           result.batches.append(recordBatch)
-        } catch let error as ArrowError {
+        case .failure(let error):
           return .failure(error)
-        } catch {
-          return .failure(.unknownError("Unexpected error: \(error)"))
         }
       default:
         return .failure(.unknownError("Unhandled header type: \(message.headerType)"))
@@ -429,17 +427,16 @@ public class ArrowReader {  // swiftlint:disable:this type_body_length
       }
     case .recordbatch:
       let rbMessage = message.header(type: org_apache_arrow_flatbuf_RecordBatch.self)!
-      do {
-        let recordBatch = try loadRecordBatch(
-          rbMessage, schema: result.messageSchema!, arrowSchema: result.schema!,
-          data: dataBody, messageEndOffset: 0
-        ).get()
+      let recordBatchResult = try loadRecordBatch(
+        rbMessage, schema: result.messageSchema!, arrowSchema: result.schema!,
+        data: dataBody, messageEndOffset: 0
+      )
+      switch recordBatchResult {
+      case .success(let recordBatch):
         result.batches.append(recordBatch)
         return .success(())
-      } catch let error as ArrowError {
+      case .failure(let error):
         return .failure(error)
-      } catch {
-        return .failure(.unknownError("Unexpected error: \(error)"))
       }
     default:
       return .failure(.unknownError("Unhandled header type: \(message.headerType)"))