feat: Add user-friendly error messages

convertPheno_client/src/code/utils/errorMessages.js

@@ -0,0 +1,9 @@
+const errorMessages = {
+  "TypeError: Cannot read properties of undefined (reading 'map')": "An unexpected error occurred while processing your data. Please try again.",
+  "Error: Request failed with status code 404": "The requested resource could not be found. Please check your input and try again.",
+  "Error: Network Error": "A network error occurred. Please check your internet connection and try again."
+};
+
+export function getFriendlyErrorMessage(errorMessage) {
+  return errorMessages[errorMessage] || "An unexpected error occurred. Please try again.";
+}