Code Modernisation: Fix known instances of array access on data types that can't be accessed as arrays.

PHP 7.4 addes a warning when trying access a null/bool/int/float/resource (everything but array, string and object) as if it were an array.

This change fixes all of these warnings visible in unit tests.

Props jrf.
See #47704.




git-svn-id: https://develop.svn.wordpress.org/trunk@45639 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/wp-db.php

@@ -3113,7 +3113,7 @@ class wpdb {
 			foreach ( $data as $col => $value ) {
 				if ( ! empty( $value['db'] ) ) {
 					// We're going to need to truncate by characters or bytes, depending on the length value we have.
-					if ( 'byte' === $value['length']['type'] ) {
+					if ( isset( $value['length']['type'] ) && 'byte' === $value['length']['type'] ) {
 						// Using binary causes LEFT() to truncate by bytes.
 						$charset = 'binary';
 					} else {