GH-36319: [Go][Parquet] Improved row group writer error messages (#36320

)

### Rationale for this change

### What changes are included in this PR?

Updated error messages for mismatched column row counts to help identify the column, or rowgroup index which failed the check, and how many rows were expected vs found.

### Are these changes tested?

Yes.

### Are there any user-facing changes?

No.

* Closes: #36319

Authored-by: Mark Wolfe <mark@wolfe.id.au>
Signed-off-by: Matt Topol <zotthewizard@gmail.com>

go/parquet/file/file_writer_test.go

@@ -139,7 +139,9 @@ func (t *SerializeTestSuite) unequalNumRows(maxRows int64, rowsPerCol []int64) {
 		t.WriteBatchSubset(int(rowsPerCol[col]), 0, cw, t.DefLevels[:rowsPerCol[col]], nil)
 		cw.Close()
 	}
-	t.Error(rgw.Close())
+	err := rgw.Close()
+	t.Error(err)
+	t.ErrorContains(err, "row mismatch for unbuffered row group")
 }
 
 func (t *SerializeTestSuite) unequalNumRowsBuffered(maxRows int64, rowsPerCol []int64) {
@@ -154,7 +156,9 @@ func (t *SerializeTestSuite) unequalNumRowsBuffered(maxRows int64, rowsPerCol []
 		t.WriteBatchSubset(int(rowsPerCol[col]), 0, cw, t.DefLevels[:rowsPerCol[col]], nil)
 		cw.Close()
 	}
-	t.Error(rgw.Close())
+	err := rgw.Close()
+	t.Error(err)
+	t.ErrorContains(err, "row mismatch for buffered row group")
 }
 
 func (t *SerializeTestSuite) TestZeroRows() {

go/parquet/file/row_group_writer.go

@@ -110,13 +110,13 @@ func (rg *rowGroupWriter) checkRowsWritten() error {
 		if rg.nrows == 0 {
 			rg.nrows = current
 		} else if rg.nrows != current {
-			return xerrors.New("row mismatch")
+			return xerrors.Errorf("row mismatch for unbuffered row group: %d, count expected: %d, actual: %d", rg.ordinal, current, rg.nrows)
 		}
 	} else if rg.buffered {
 		current := rg.columnWriters[0].RowsWritten()
-		for _, wr := range rg.columnWriters[1:] {
+		for i, wr := range rg.columnWriters[1:] {
 			if current != wr.RowsWritten() {
-				return xerrors.New("row mismatch error")
+				return xerrors.Errorf("row mismatch for buffered row group: %d, column: %d, count expected: %d, actual: %d", rg.ordinal, i+1, current, wr.RowsWritten())
 			}
 		}
 		rg.nrows = current
@@ -182,7 +182,7 @@ func (rg *rowGroupWriter) Column(i int) (ColumnChunkWriter, error) {
 	if i >= 0 && i < len(rg.columnWriters) {
 		return rg.columnWriters[i], nil
 	}
-	return nil, xerrors.New("invalid column number requested")
+	return nil, xerrors.Errorf("invalid column number requested: %d", i)
 }
 
 func (rg *rowGroupWriter) CurrentColumn() int { return rg.metadata.CurrentColumn() }