Add component ID to error message

Closes #3462700

core/lib/Drupal/Core/Theme/Component/ComponentValidator.php

@@ -138,7 +138,7 @@ public function validateDefinition(array $definition, bool $enforce_schemas): bo
       ...$message_parts,
       ...$missing_class_errors,
     ];
-    $message = implode("/n", $message_parts);
+    $message = implode("\n", $message_parts);
     // Throw the exception with the error message.
     throw new InvalidComponentException($message);
   }
@@ -208,7 +208,7 @@ function (array $error) use ($context): bool {
       return TRUE;
     }
     $message_parts = array_map(
-      static function (array $error): string {
+      static function (array $error) use ($component_id, $context): string {
         // We check the error message instead of values and definitions here
         // because it's hard to access both given the possible complexity of a
         // schema. Since this is a small non critical DX improvement error
@@ -217,11 +217,17 @@ static function (array $error): string {
           $error['message'] .= '. This may be because the property is empty instead of having data present. If possible fix the source data, use the |default() twig filter, or update the schema to allow multiple types.';
         }
 
-        return sprintf("[%s] %s", $error['property'], $error['message']);
+        // If the property value has been set, print it out for easier
+        // debugging.
+        if (isset($context[$error['property']]) && \is_scalar($context[$error['property']])) {
+          $error['message'] .= \sprintf('. The provided value is: "%s"', $context[$error['property']]);
+        }
+
+        return sprintf('[%s/%s] %s.', $component_id, $error['property'], $error['message']);
       },
       $errors
     );
-    $message = implode("/n", $message_parts);
+    $message = implode("\n", $message_parts);
     throw new InvalidComponentException($message);
   }
 
@@ -276,7 +282,7 @@ private function validateClassProps(array $props_schema, array $props_raw, strin
     }
     $props_schema = $this->nullifyClassPropsSchema($props_schema, $classes_per_prop);
     if (!empty($error_messages)) {
-      $message = implode("/n", $error_messages);
+      $message = implode("\n", $error_messages);
       throw new InvalidComponentException($message);
     }
     return [$props_schema, $props_raw];