fix: Fix regression NPE in binder (#18623)

This patch fixes a regression in Binder introduced by adding skipDefaultValidator API (#18549). This issue was missed since it seems to be impossible/difficult to trigger via unit testing using the mock field components in Flow project.

Affected flow-components tests:
UpdateEditorComponentIT
DynamicEditorKBNavigationIT
GridViewEditorIT.dynamicNotBufferedEditor_closeEditorUsingKeyboard
GridViewEditorIT.dynamicNotBufferedEditor
GridViewEditorIT.dynamicNotBufferedEditor_navigateUsingKeyboard

Fixes #18608

flow-data/src/main/java/com/vaadin/flow/data/binder/Binder.java

@@ -1006,9 +1006,12 @@ protected BindingBuilderImpl(Binder<BEAN> binder,
             this.statusHandler = statusHandler;
 
             if (field instanceof HasValidator hasValidator) {
-                withValidator((val, ctx) -> binding.isDefaultValidatorDisabled()
-                        ? ValidationResult.ok()
-                        : hasValidator.getDefaultValidator().apply(val, ctx));
+                withValidator((val,
+                        ctx) -> binding != null
+                                && binding.isDefaultValidatorDisabled()
+                                        ? ValidationResult.ok()
+                                        : hasValidator.getDefaultValidator()
+                                                .apply(val, ctx));
             }
         }
 
@@ -1024,6 +1027,12 @@ public Binding<BEAN, TARGET> bind(ValueProvider<BEAN, TARGET> getter,
 
             BindingImpl<BEAN, FIELDVALUE, TARGET> binding = new BindingImpl<>(
                     this, getter, setter);
+            // Setting the binding field value has been moved up here to fix a
+            // regression NPE https://github.com/vaadin/flow/issues/18608 which
+            // breaks tests of Grid component: UpdateEditorComponentIT,
+            // DynamicEditorKBNavigationIT and
+            // GridViewEditorIT.dynamicNotBufferedEditor*
+            this.binding = binding;
 
             // Remove existing binding for same field to avoid potential
             // multiple application of converter
@@ -1042,7 +1051,6 @@ public Binding<BEAN, TARGET> bind(ValueProvider<BEAN, TARGET> getter,
             if (getBinder().incompleteBindings != null) {
                 getBinder().incompleteBindings.remove(getField());
             }
-            this.binding = binding;
 
             return binding;
         }