fix(example): update validation to throw on empty values

example/lib/main.dart

@@ -129,7 +129,7 @@ class _MyFormState extends State<MyForm> {
               labelText: 'Email',
               helperText: 'A valid email e.g. [email protected]',
             ),
-            validator: (_) => _state.email.displayError?.text(),
+            validator: (value) => _state.email.validator(value ?? '')?.text(),
             keyboardType: TextInputType.emailAddress,
             textInputAction: TextInputAction.next,
           ),
@@ -143,7 +143,8 @@ class _MyFormState extends State<MyForm> {
               labelText: 'Password',
               errorMaxLines: 2,
             ),
-            validator: (_) => _state.password.displayError?.text(),
+            validator: (value) =>
+                _state.password.validator(value ?? '')?.text(),
             obscureText: true,
             textInputAction: TextInputAction.done,
           ),
@@ -188,7 +189,7 @@ class MyFormState with FormzMixin {
   List<FormzInput<dynamic, dynamic>> get inputs => [email, password];
 }
 
-enum EmailValidationError { invalid }
+enum EmailValidationError { invalid, empty }
 
 class Email extends FormzInput<String, EmailValidationError>
     with FormzInputErrorCacheMixin {
@@ -202,11 +203,17 @@ class Email extends FormzInput<String, EmailValidationError>
 
   @override
   EmailValidationError? validator(String value) {
-    return _emailRegExp.hasMatch(value) ? null : EmailValidationError.invalid;
+    if (value.isEmpty) {
+      return EmailValidationError.empty;
+    } else if (!_emailRegExp.hasMatch(value)) {
+      return EmailValidationError.invalid;
+    }
+
+    return null;
   }
 }
 
-enum PasswordValidationError { invalid }
+enum PasswordValidationError { invalid, empty }
 
 class Password extends FormzInput<String, PasswordValidationError> {
   const Password.pure([super.value = '']) : super.pure();
@@ -218,9 +225,13 @@ class Password extends FormzInput<String, PasswordValidationError> {
 
   @override
   PasswordValidationError? validator(String value) {
-    return _passwordRegex.hasMatch(value)
-        ? null
-        : PasswordValidationError.invalid;
+    if (value.isEmpty) {
+      return PasswordValidationError.empty;
+    } else if (!_passwordRegex.hasMatch(value)) {
+      return PasswordValidationError.invalid;
+    }
+
+    return null;
   }
 }
 
@@ -229,6 +240,8 @@ extension on EmailValidationError {
     switch (this) {
       case EmailValidationError.invalid:
         return 'Please ensure the email entered is valid';
+      case EmailValidationError.empty:
+        return 'Please enter an email';
     }
   }
 }
@@ -238,6 +251,8 @@ extension on PasswordValidationError {
     switch (this) {
       case PasswordValidationError.invalid:
         return '''Password must be at least 8 characters and contain at least one letter and number''';
+      case PasswordValidationError.empty:
+        return 'Please enter a password';
     }
   }
 }