TypeError: Cannot read properties of null (reading 'forEach')

ChamaraNandasena

getting below error and cannot identify the reason

tasha

Hello ChamaraNandasena
I created a basic working example, and everything functions correctly.
You can check it out here:https://stackblitz.com/edit/vitejs-vite-2cub3aaf?file=src%2FGanttComponent.jsx

I recommend that you compare your implementation with the example provided. If the issue persists, please share your code so that I can help you troubleshoot further.

Also to fix the error please ensure that the data being passed to the Gantt component is not null or undefined at the time of rendering.

ChamaraNandasena

Thanks, I managed to get the gantt populated with data

ChamaraNandasena

getting the same error again seems error triggered in bundle.js

function ThemeProvider(_ref) { let { theme: themeInput } = _ref, props = (0,_babel_runtime_helpers_esm_objectWithoutPropertiesLoose__WEBPACK_IMPORTED_MODULE_1__["default"])(_ref, _excluded); const scopedTheme = themeInput[_identifier__WEBPACK_IMPORTED_MODULE_5__["default"]];

ChamaraNandasena

drill down the issue - is that when there is a single summary task it gives me the error
export const sampleTasks = [ // Parent task - Project Planning { id: 1, text: 'Project Planning', start: new Date(2025, 11, 1, 8, 0), // December 1, 2025, 8:00 AM end: new Date(2025, 11, 8, 17, 0), // December 8, 2025, 5:00 PM type: 'summary', open: true, progress: 60, }, ];

tasha

If a task doesn't have subtasks, the open parameter should be set to false.

Please check the example: https://stackblitz.com/edit/vitejs-vite-2cub3aaf?file=src%2FGanttComponent.jsx