MDL-77097 store_mongodb: keep compatibility with PHP 7.4

Replaced 4 occurrences of get_debug_type() by gettype() to keep PHP 7.4 compatibility. Note this
has not been applied to 4.2dev and up because, there, it's safe to use get_debug_type().

cache/stores/mongodb/MongoDB/Exception/InvalidArgumentException.php

@@ -20,7 +20,7 @@
 use MongoDB\Driver\Exception\InvalidArgumentException as DriverInvalidArgumentException;
 use function array_pop;
 use function count;
-use function get_debug_type;
+use function gettype;
 use function implode;
 use function is_array;
 use function sprintf;
@@ -56,6 +56,6 @@ public static function invalidType($name, $value, $expectedType)
             $expectedType = $typeString;
         }
 
-        return new static(sprintf('Expected %s to have type "%s" but found "%s"', $name, $expectedType, get_debug_type($value)));
+        return new static(sprintf('Expected %s to have type "%s" but found "%s"', $name, $expectedType, gettype($value)));
     }
 }

cache/stores/mongodb/MongoDB/Exception/ResumeTokenException.php

@@ -17,7 +17,7 @@
 
 namespace MongoDB\Exception;
 
-use function get_debug_type;
+use function gettype;
 use function sprintf;
 
 class ResumeTokenException extends RuntimeException
@@ -30,7 +30,7 @@ class ResumeTokenException extends RuntimeException
      */
     public static function invalidType($value)
     {
-        return new static(sprintf('Expected resume token to have type "array or object" but found "%s"', get_debug_type($value)));
+        return new static(sprintf('Expected resume token to have type "array or object" but found "%s"', gettype($value)));
     }
 
     /**

cache/stores/mongodb/readme_moodle.txt

@@ -10,3 +10,7 @@ Import procedure:
 - Check the minim php driver version in https://docs.mongodb.com/drivers/php#compatibility and change the value in the "are_requirements_met" method if necessary.
 
 This version (1.8.0) requires PHP mongodb extension >= 1.8.0
+
+Local changes:
+- Replaced 4 occurrences of get_debug_type() by gettype() to keep PHP 7.4 compatibility. Note this
+  has not been applied to 4.2dev and up because, there, it's safe to use get_debug_type().