Client Script Errors — Diagnosis and Resolution

Cross-refs: frappe-syntax-clientscripts (syntax), frappe-impl-clientscripts (workflows), frappe-errors-serverscripts (server-side).

Error Diagnosis Flowchart

ERROR IN CLIENT SCRIPT
│
├─► TypeError: Cannot read properties of undefined
│   ├─► "frm.doc.fieldname" → Field does not exist on DocType
│   ├─► "r.message.value" → Server returned null/error
│   └─► "row.fieldname" in child table → Row not fetched correctly
│
├─► frappe.call fails silently
│   ├─► Missing error callback → Add error handler
│   ├─► 403 Forbidden → Method not whitelisted (@frappe.whitelist)