Fix in Container and added Program:stop()

Author: NoryiE

src/elements/Container.lua

@@ -301,6 +301,7 @@ end
 --- @param child table The child to remove
 --- @return Container self The container instance
 function Container:removeChild(child)
+    if child == nil then return self end
     for i,v in ipairs(self._values.children) do
         if v.get("id") == child.get("id") then
             table.remove(self._values.children, i)

src/elements/Program.lua

@@ -184,6 +184,19 @@ function Program:execute(path, env, addEnvironment)
     return self
 end
 
+--- Stops the program
+--- @shortDescription Stops the program
+--- @return Program self The Program instance
+function Program:stop()
+    local program = self.get("program")
+    if program then
+        program:stop()
+        self.set("running", false)
+        self.set("program", nil)
+    end
+    return self
+end
+
 --- Sends an event to the program
 --- @shortDescription Sends an event to the program
 --- @param event string The event to send