diff --git a/4dev/tests/Convert/CoreLibsConvertStringsTest.php b/4dev/tests/Convert/CoreLibsConvertStringsTest.php
index 3233ce07..ed4bbc97 100644
--- a/4dev/tests/Convert/CoreLibsConvertStringsTest.php
+++ b/4dev/tests/Convert/CoreLibsConvertStringsTest.php
@@ -135,6 +135,11 @@ final class CoreLibsConvertStringsTest extends TestCase
 	public function splitFormatStringExceptionProvider(): array
 	{
 		return [
+			'string format with no splitter match' => [
+				'1234',
+				'22',
+				'12-34'
+			],
 			'invalid format string' => [
 				'1234',
 				'2あ2',
diff --git a/www/admin/class_test.array.php b/www/admin/class_test.array.php
index 87146eaf..439252f3 100644
--- a/www/admin/class_test.array.php
+++ b/www/admin/class_test.array.php
@@ -333,7 +333,7 @@ print "(kosrt, lower case, reverse): "
 print "<hr>";
 $nested = [
 	'B' => 'foo', 'a', '0', 9,
-	1 => ['z', 'b', 'a'],
+	'1' => ['z', 'b', 'a'],
 	'd' => ['zaip', 'bar', 'baz']
 ];
 print "Nested: " . DgS::printAr($nested) . "<br>";
diff --git a/www/lib/CoreLibs/Combined/ArrayHandler.php b/www/lib/CoreLibs/Combined/ArrayHandler.php
index 16d2c3ab..4bf3b99d 100644
--- a/www/lib/CoreLibs/Combined/ArrayHandler.php
+++ b/www/lib/CoreLibs/Combined/ArrayHandler.php
@@ -251,10 +251,10 @@ class ArrayHandler
 	 * @param  array<mixed>          $array
 	 * @param  string|int|float|bool $search_value
 	 * @param  string|array<string>  $required_key
-	 * @param  ?string               $serach_key [null]
+	 * @param  ?string               $search_key [null]
 	 * @param  string                $path_separator [DATA_SEPARATOR]
 	 * @param  string                $current_path
-	 * @return array<array{content?:array<mixed>,path?:string,missing_key?:string}>
+	 * @return array<array{content?:array<mixed>,path?:string,missing_key?:array<string>}>
 	 */
 	public static function findArraysMissingKey(
 		array $array,
diff --git a/www/lib/CoreLibs/Convert/Strings.php b/www/lib/CoreLibs/Convert/Strings.php
index ae87c4d2..30d4ad44 100644
--- a/www/lib/CoreLibs/Convert/Strings.php
+++ b/www/lib/CoreLibs/Convert/Strings.php
@@ -85,7 +85,12 @@ class Strings
 			);
 		}
 		// get the split characters that are not numerical and check they are ascii
-		$split_characters = self::removeDuplicates(preg_replace('/[0-9]/', '', $split_format));
+		$split_characters = self::removeDuplicates(preg_replace('/[0-9]/', '', $split_format) ?: '');
+		if (empty($split_characters)) {
+			throw new \InvalidArgumentException(
+				"A split character must exist in the format string: " . $split_format
+			);
+		}
 		if (preg_match('/[^\x20-\x7e]/', $split_characters)) {
 			throw new \InvalidArgumentException(
 				"The split character has to be a valid ascii character: " . $split_characters
@@ -296,7 +301,7 @@ class Strings
 	 * check if a regex is invalid, returns array with flag and error string
 	 *
 	 * @param  string $pattern
-	 * @return array{valid:bool,preg_error:0,error:null|string,pcre_error:null|string}
+	 * @return array{valid:bool,preg_error:int,error:null|string,pcre_error:null|string}
 	 */
 	public static function validateRegex(string $pattern): array
 	{