feat: Update validation error to include original value

Prior, the validation error may contain the cast-value which can be confusing when reporting the validation error to users.

Author: courtney-miles

src/Fields/BaseField.php

@@ -171,6 +171,12 @@ public function validateValue($val)
 
             return [];
         } catch (FieldValidationException $e) {
+            foreach ($e->validationErrors as $ve) {
+                // Replace the cast-value for the violation, with the original value.
+                // This so the error message contains the original representation of the invalid value.
+                $ve->extraDetails['value'] = $val;
+            }
+
             return $e->validationErrors;
         }
     }

tests/Fields/BaseFieldTest.php

@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Fields;
+
+use frictionlessdata\tableschema\Fields\BaseField;
+use PHPUnit\Framework\TestCase;
+use ZBan\Tests\PHPUnit\Framework\ZBanTestCase;
+
+/**
+ * @covers \frictionlessdata\tableschema\Fields\BaseField
+ */
+class BaseFieldTest extends TestCase
+{
+    public function testPreserveOriginalValueInValidationError(): void
+    {
+        $descriptor = (object) [
+            'name' => 'date_col',
+            'constraints' => (object) ['minimum' => '2025-07-01']
+        ];
+
+        $sut = new class($descriptor) extends BaseField {
+            protected function validateCastValue($val)
+            {
+                // If the logic is wrong, this object will be in the error
+                // instead of the original date string.
+                return new \DateTimeImmutable($val);
+            }
+        };
+
+        $validatedValue = '2025-06-30';
+        $errors = $sut->validateValue($validatedValue);
+
+        self::assertCount(1, $errors);
+        $error = reset($errors);
+        self::assertSame(
+            $validatedValue,
+            $error->extraDetails['value']
+        );
+    }
+}