[form] Fix reading title from undefined schema

Author: x0k

.changeset/dry-falcons-notice.md

@@ -0,0 +1,5 @@
+---
+"@sjsf/form": patch
+---
+
+Fix reading `title` from `undefined` schema

packages/form/src/form/fields/object/object-field.svelte

@@ -116,7 +116,7 @@
   {#if schemaProperties !== undefined && value !== undefined}
     {#each schemaPropertiesOrder as property (property)}
       {@const isAdditional = isAdditionalProperty(schemaProperties, property)}
-      {@const propSchemaDefinition = schemaProperties[property]!}
+      {@const propSchemaDefinition = schemaProperties[property] ?? false}
       {@const propSchema = typeof propSchemaDefinition === "boolean" ? {} : propSchemaDefinition}
       {@const propUiSchema =
         (isAdditional ? config.uiSchema.additionalProperties : config.uiSchema[property]) as UiSchema ?? {}}