AP_Scripting: CAN: `get_device` and `get_device2` return nil if no driver is configure with the correct protocol

libraries/AP_Scripting/docs/docs.lua

@@ -344,14 +344,14 @@ function efi:get_backend(instance) end
 ---@class CAN
 CAN = {}
 
--- get a CAN bus device handler first scripting driver
+-- get a CAN bus device handler first scripting driver, will return nil if no driver with protocol Scripting is configured
 ---@param buffer_len uint32_t_ud -- buffer length 1 to 25
----@return ScriptingCANBuffer_ud
+---@return ScriptingCANBuffer_ud|nil
 function CAN:get_device(buffer_len) end
 
--- get a CAN bus device handler second scripting driver
+-- get a CAN bus device handler second scripting driver, will return nil if no driver with protocol Scripting2 is configured
 ---@param buffer_len uint32_t_ud -- buffer length 1 to 25
----@return ScriptingCANBuffer_ud
+---@return ScriptingCANBuffer_ud|nil
 function CAN:get_device2(buffer_len) end
 
 -- Auto generated binding

libraries/AP_Scripting/lua_bindings.cpp

@@ -682,6 +682,12 @@ int lua_get_CAN_device(lua_State *L) {
         }
     }
 
+    if (!scripting->_CAN_dev->initialized()) {
+        // Driver not initialized, probably because there is no can driver set to scripting
+        // Return nil
+        return 0;
+    }
+
     new_ScriptingCANBuffer(L);
     *((ScriptingCANBuffer**)luaL_checkudata(L, -1, "ScriptingCANBuffer")) = scripting->_CAN_dev->add_buffer(buffer_len);
 
@@ -707,6 +713,12 @@ int lua_get_CAN_device2(lua_State *L) {
         }
     }
 
+    if (!scripting->_CAN_dev2->initialized()) {
+        // Driver not initialized, probably because there is no can driver set to scripting 2
+        // Return nil
+        return 0;
+    }
+
     new_ScriptingCANBuffer(L);
     *((ScriptingCANBuffer**)luaL_checkudata(L, -1, "ScriptingCANBuffer")) = scripting->_CAN_dev2->add_buffer(buffer_len);