Check for nil row from Execer

CHANGELOG.md

@@ -1,3 +1,6 @@
+## 3.9.2 (unreleased)
+- [PR #253](https://github.com/rqlite/rqlite/pull/254): Handle nil row returned by SQL execer. Fixes [issue #253](https://github.com/rqlite/rqlite/issues/253).
+
 ## 3.9.1 (December 29th 2016)
 - [PR #247](https://github.com/rqlite/rqlite/pull/247): Simplify loading of SQLite dump files via single command execution. Fixes [issue #246](https://github.com/rqlite/rqlite/issues/246).
 - [PR #247](https://github.com/rqlite/rqlite/pull/247): Correct SQLite dump load authentication check.

db/db.go

@@ -247,6 +247,9 @@ func (db *DB) Execute(queries []string, tx, xTime bool) ([]*Result, error) {
 				}
 				break
 			}
+			if r == nil {
+				continue
+			}
 
 			lid, err := r.LastInsertId()
 			if err != nil {

db/db_test.go

@@ -82,6 +82,21 @@ func Test_LoadInMemory(t *testing.T) {
 	}
 }
 
+func Test_EmptyStatements(t *testing.T) {
+	db, path := mustCreateDatabase()
+	defer db.Close()
+	defer os.Remove(path)
+
+	_, err := db.Execute([]string{""}, false, false)
+	if err != nil {
+		t.Fatalf("failed to execute empty statement: %s", err.Error())
+	}
+	_, err = db.Execute([]string{";"}, false, false)
+	if err != nil {
+		t.Fatalf("failed to execute empty statement with semicolon: %s", err.Error())
+	}
+}
+
 func Test_SimpleSingleStatements(t *testing.T) {
 	db, path := mustCreateDatabase()
 	defer db.Close()