List tables: Even more robust fallback for the primary column.

Since `WP_List_Table::get_default_primary_column()` can be overridden in a subclass and columns can be further filtered, it is possible to end up with a primary column that no longer exists. This is particularly evident in list tables for custom post types that have been altered via filter.

props ocean90.
fixes #32996.

Built from https://develop.svn.wordpress.org/trunk@33266


git-svn-id: http://core.svn.wordpress.org/trunk@33238 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/class-wp-list-table.php

@@ -887,6 +887,12 @@ class WP_List_Table {
 		$columns = $this->get_columns();
 		$default = $this->get_default_primary_column_name();
 
+		// If the primary column doesn't exist fall back to the
+		// first non-checkbox column.
+		if ( ! isset( $columns[ $default ] ) ) {
+			$default = WP_List_Table::get_default_primary_column_name();
+		}
+
 		/**
 		 * Filter the name of the primary column for the current list table.
 		 *

wp-admin/includes/class-wp-posts-list-table.php

@@ -1069,7 +1069,7 @@ class WP_Posts_List_Table extends WP_List_Table {
 	 * @return string Name of the default primary column, in this case, 'title'.
 	 */
 	protected function get_default_primary_column_name() {
-		return( 'title' );
+		return 'title';
 	}
 
 	/**

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.3-beta2-33265';
+$wp_version = '4.3-beta2-33266';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.