fix(sdk-go): Catch nil value early when converting interface to var val (#1271)

Author: Snarr

sdk-go/littlehorse/lh_variables.go

@@ -3,9 +3,10 @@ package littlehorse
 import (
 	"encoding/base64"
 	"encoding/json"
-	"github.com/littlehorse-enterprises/littlehorse/sdk-go/lhproto"
 	"reflect"
 	"strconv"
+
+	"github.com/littlehorse-enterprises/littlehorse/sdk-go/lhproto"
 )
 
 func StrToVarVal(input string, varType lhproto.VariableType) (*lhproto.VariableValue, error) {
@@ -143,6 +144,10 @@ func GetVarType(thing interface{}) *lhproto.VariableType {
 }
 
 func InterfaceToVarVal(someInterface interface{}) (*lhproto.VariableValue, error) {
+	if someInterface == nil {
+		return &lhproto.VariableValue{}, nil
+	}
+
 	out := &lhproto.VariableValue{}
 	var err error
 
@@ -152,9 +157,6 @@ func InterfaceToVarVal(someInterface interface{}) (*lhproto.VariableValue, error
 	}
 
 	isPtr, _ := GetIsPtrAndType(reflect.TypeOf(someInterface))
-	if someInterface == nil {
-		return &lhproto.VariableValue{}, nil
-	}
 
 	var actualThing interface{}
 	if isPtr {