diff --git a/adminer/include/auth.inc.php b/adminer/include/auth.inc.php
index 66abb111..ebf3b63f 100644
--- a/adminer/include/auth.inc.php
+++ b/adminer/include/auth.inc.php
@@ -61,8 +61,8 @@ function check_invalid_login() {
 			break;
 		}
 	}
-	$invalid = ($invalids ? $invalids[$adminer->bruteForceKey()] : array());
-	$next_attempt = (idx($invalid, 1) > 29 ? $invalid[0] - time() : 0); // allow 30 invalid attempts
+	$invalid = idx($invalids, $adminer->bruteForceKey(), array());
+	$next_attempt = ($invalid[1] > 29 ? $invalid[0] - time() : 0); // allow 30 invalid attempts
 	if ($next_attempt > 0) { //! do the same with permanent login
 		auth_error(lang('Too many unsuccessful logins, try again in %d minute(s).', ceil($next_attempt / 60)));
 	}
diff --git a/adminer/include/functions.inc.php b/adminer/include/functions.inc.php
index 95cdde83..7292c4af 100644
--- a/adminer/include/functions.inc.php
+++ b/adminer/include/functions.inc.php
@@ -66,6 +66,7 @@ function escape_string($val) {
 }
 
 /** Get a possibly missing item from a possibly missing array
+* idx($row, $key) is better than $row[$key] ?? null because it reports error for undefined $row
 * @param array|null
 * @param string|int
 * @param mixed
@@ -312,7 +313,7 @@ function where($where, $fields = array()) {
 	foreach ((array) $where["where"] as $key => $val) {
 		$key = bracket_escape($key, 1); // 1 - back
 		$column = escape_key($key);
-		$field = ($fields ? $fields[$key] : array());
+		$field = idx($fields, $key, array());
 		$field_type = $field["type"];
 		$return[] = $column
 			. (JUSH == "sql" && $field_type == "json" ? " = CAST(" . q($val) . " AS JSON)"
diff --git a/adminer/sql.inc.php b/adminer/sql.inc.php
index 3bce84d1..6fdc849e 100644
--- a/adminer/sql.inc.php
+++ b/adminer/sql.inc.php
@@ -230,7 +230,7 @@ if (!isset($_GET["import"])) {
 	} elseif ($_GET["history"] == "all") {
 		$q = $history;
 	} elseif ($_GET["history"] != "") {
-		$q = $history[$_GET["history"]][0];
+		$q = idx($history[$_GET["history"]], 0);
 	}
 	echo "<p>";
 	textarea("query", $q, 20);
diff --git a/plugins/codemirror.php b/plugins/codemirror.php
index 6d108a65..f7c05070 100644
--- a/plugins/codemirror.php
+++ b/plugins/codemirror.php
@@ -72,7 +72,7 @@ for (const el of qsa('textarea')) {
 			hintOptions: {
 				completeSingle: false,
 				tables: <?php echo json_encode($tables); ?>,
-				defaultTable: <?php echo json_encode($_GET["trigger"] ? $_GET["trigger"] : ($_GET["check"] ? $_GET["check"] : null)); ?>
+				defaultTable: <?php echo json_encode($_GET["trigger"] ? $_GET["trigger"] : ($_GET["check"] ?: null)); ?>
 			}
 		});
 		cm.setSize(width, height);
diff --git a/plugins/drivers/imap.php b/plugins/drivers/imap.php
index 0d236a32..9583ac69 100644
--- a/plugins/drivers/imap.php
+++ b/plugins/drivers/imap.php
@@ -122,7 +122,7 @@ if (isset($_GET["imap"])) {
 			function __construct($result) {
 				$this->result = $result;
 				$this->num_rows = count($result);
-				$this->fields = ($result ? array_keys(reset($result)) : array());
+				$this->fields = array_keys(idx($result, 0,  array()));
 			}
 
 			function fetch_assoc() {