Added some casts to make it work when other drivers are loaded

src/sqlite3/result_set.cr

@@ -18,7 +18,7 @@ class SQLite3::ResultSet < DB::ResultSet
     when LibSQLite3::Code::DONE
       false
     else
-      raise Exception.new(@statement.connection)
+      raise Exception.new(sqlite3_statement.sqlite3_connection)
     end
   end
 
@@ -41,7 +41,7 @@ class SQLite3::ResultSet < DB::ResultSet
       when Type::NULL
         nil
       else
-        raise Exception.new(@statement.connection)
+        raise Exception.new(sqlite3_statement.sqlite3_connection)
       end
     @column_index += 1
     value
@@ -68,12 +68,16 @@ class SQLite3::ResultSet < DB::ResultSet
   end
 
   def to_unsafe
-    @statement.to_unsafe
+    sqlite3_statement.to_unsafe
   end
 
   # :nodoc:
   private def step
-    LibSQLite3::Code.new LibSQLite3.step(@statement)
+    LibSQLite3::Code.new LibSQLite3.step(sqlite3_statement)
+  end
+
+  protected def sqlite3_statement
+    @statement.as(Statement)
   end
 
   private def moving_column

src/sqlite3/statement.cr

@@ -1,7 +1,7 @@
 class SQLite3::Statement < DB::Statement
   def initialize(connection, sql)
     super(connection)
-    check LibSQLite3.prepare_v2(@connection, sql, sql.bytesize + 1, out @stmt, nil)
+    check LibSQLite3.prepare_v2(sqlite3_connection, sql, sql.bytesize + 1, out @stmt, nil)
   end
 
   protected def perform_query(args : Enumerable) : DB::ResultSet
@@ -17,8 +17,8 @@ class SQLite3::Statement < DB::Statement
     rs.move_next
     rs.close
 
-    rows_affected = LibSQLite3.changes(connection).to_i64
+    rows_affected = LibSQLite3.changes(sqlite3_connection).to_i64
-    last_id = LibSQLite3.last_insert_rowid(connection)
+    last_id = LibSQLite3.last_insert_rowid(sqlite3_connection)
 
     DB::ExecResult.new rows_affected, last_id
   end
@@ -65,7 +65,11 @@ class SQLite3::Statement < DB::Statement
   end
 
   private def check(code)
-    raise Exception.new(@connection) unless code == 0
+    raise Exception.new(sqlite3_connection) unless code == 0
+  end
+
+  protected def sqlite3_connection
+    @connection.as(Connection)
   end
 
   def to_unsafe