do some error checking before asserting orderedmap

cmd/main/main.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"log"
 	"os"
+	"reflect"
 	"time"
 	"unicode/utf8"
 
@@ -102,11 +103,18 @@ func main() {
 	if !ok {
 		fmt.Printf("Missing key for multitype array")
 	}
+
 	// Get an interface that we can work with to access the sub elements
 	vslice := vislice.([]interface{})
 
+	// Check that the first element is what we expected
+	if _, ok := vslice[0].(orderedmap.OrderedMap); !ok {
+		error := fmt.Sprintf("Type of first vslice element is not an ordered map. It appears to be '%v'\n", reflect.TypeOf(vslice[0]))
+		panic(error)
+	}
 	// Get the keys for the first element so we know what the column names will be
 	columnMap := vslice[0].(orderedmap.OrderedMap)
+	fmt.Printf("First vslice element is an ordered map")
 	columnNames := columnMap.Keys()
 
 	// Run code to add column names to the first row of the workbook