Nil pointer access due to empty chunk returned from gosnowflake.build…

…FirstArrowChunk

Modify gosnowflake.buildFirstArrowChunk to return an error and pass it
back up the call stack.

The following three tests fail additionally compared to upstream, which
is expected (see 'Maintaining the gosnowflake fork'):

> TestPutGetFile
> TestPutGetStream
> TestPutGetGcsDownscopedCredential

arrow_chunk.go

@@ -68,15 +68,15 @@ func (arc *arrowResultChunk) decodeArrowBatch(scd *snowflakeChunkDownloader) (*[
 }
 
 // Build arrow chunk based on RowSet of base64
-func buildFirstArrowChunk(rowsetBase64 string, loc *time.Location, alloc memory.Allocator) arrowResultChunk {
+func buildFirstArrowChunk(rowsetBase64 string, loc *time.Location, alloc memory.Allocator) (arrowResultChunk, error) {
 	rowSetBytes, err := base64.StdEncoding.DecodeString(rowsetBase64)
 	if err != nil {
-		return arrowResultChunk{}
+		return arrowResultChunk{}, err
 	}
 	rr, err := ipc.NewReader(bytes.NewReader(rowSetBytes), ipc.WithAllocator(alloc))
 	if err != nil {
-		return arrowResultChunk{}
+		return arrowResultChunk{}, err
 	}
 
-	return arrowResultChunk{rr, 0, loc, alloc}
+	return arrowResultChunk{rr, 0, loc, alloc}, nil
 }

chunk_downloader.go

@@ -109,7 +109,10 @@ func (scd *snowflakeChunkDownloader) start() error {
 		if scd.sc != nil && scd.sc.cfg != nil {
 			loc = getCurrentLocation(scd.sc.cfg.Params)
 		}
-		firstArrowChunk := buildFirstArrowChunk(scd.RowSet.RowSetBase64, loc, scd.pool)
+		firstArrowChunk, err := buildFirstArrowChunk(scd.RowSet.RowSetBase64, loc, scd.pool)
+		if err != nil {
+			return err
+		}
 		higherPrecision := higherPrecisionEnabled(scd.ctx)
 		scd.CurrentChunk, err = firstArrowChunk.decodeArrowChunk(scd.RowSet.RowType, higherPrecision)
 		scd.CurrentChunkSize = firstArrowChunk.rowCount
@@ -274,7 +277,10 @@ func (scd *snowflakeChunkDownloader) startArrowBatches() error {
 	if scd.sc != nil && scd.sc.cfg != nil {
 		loc = getCurrentLocation(scd.sc.cfg.Params)
 	}
-	firstArrowChunk := buildFirstArrowChunk(scd.RowSet.RowSetBase64, loc, scd.pool)
+	firstArrowChunk, err := buildFirstArrowChunk(scd.RowSet.RowSetBase64, loc, scd.pool)
+	if err != nil {
+		return err
+	}
 	scd.FirstBatch = &ArrowBatch{
 		idx:                0,
 		scd:                scd,