From 604cea7a73474808a78da18cebd43d90926b0575 Mon Sep 17 00:00:00 2001
From: Nikodem Bernat <n.bernat@outlook.com>
Date: Tue, 23 Jan 2024 17:05:02 +0100
Subject: [PATCH] Add a message to an assertion

---
 lib/src/form_builder.dart | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/src/form_builder.dart b/lib/src/form_builder.dart
index 9af6b070a..040030fc5 100644
--- a/lib/src/form_builder.dart
+++ b/lib/src/form_builder.dart
@@ -221,7 +221,11 @@ class FormBuilderState extends State<FormBuilder> {
   }
 
   void unregisterField(String name, FormBuilderFieldState field) {
-    assert(_fields.containsKey(name));
+    assert(
+      _fields.containsKey(name),
+      'Failed to unregister a field. Make sure that all field names in a form are unique.',
+    );
+
     // Only remove the field when it is the one registered.  It's possible that
     // the field is replaced (registerField is called twice for a given name)
     // before unregisterField is called for the name, so just emit a warning