diff --git a/developing.md b/developing.md
index ecccf1d4..160b125a 100644
--- a/developing.md
+++ b/developing.md
@@ -81,11 +81,11 @@ All functions have doc-comments, but redundancy is avoided. For example, `Db` me
 
 Inline comments are useful for linking specifications but are generally avoided for explaining self-explanatory code. They start with a lowercase letter and do not end with a period, though I am not entirely happy with this convention.
 
-Comments starting with `//!` mean TODO.
+Comments starting with `//!` mean TODO. Comments starting with `//~` are meant for debugging.
 
 ## Error Handling
 
-Adminer strictly initializes all variables before use, which is [verified](https://github.com/vrana/php-initialized). However, Adminer relies on the default value of uninitialized array items. This approach leads to more readable code. Consider the following examples:
+Adminer strictly initializes all variables before use, which is [verified](/phpstan.neon). However, Adminer relies on the default value of uninitialized array items. This approach leads to more readable code. Consider the following examples:
 
 ```php
 // Adminer style
@@ -110,7 +110,7 @@ function idx($array, $key, $default = null) {
 }
 ```
 
-Although it would be possible to use such a function in Adminer, the code would still be less readable than the current approach. Using `isset` can introduce bugs, such as in this case: `isset($rw["name"])`. Here, I intended to check if `$row` contains `name`, but a typo in the variable name is silently ignored. `empty()` is even worse and should be avoided in most cases.
+Although it would be possible to use such a function in Adminer, the code would still be less readable than the current approach. Using `isset` can introduce bugs, such as in this case: `isset($rw["name"])`. Here, I intended to check if `$row` contains `name`, but a typo in the variable name is silently ignored. The same is true for `??`. `empty()` is even worse and should be avoided in most cases.
 
 Adminer uses `@` only where an error is unavoidable, such as when writing to files. Even if you check whether a file is writable, a race condition exists between the check and the actual write operation.
 
diff --git a/phpstan.neon b/phpstan.neon
index f6527337..ea25c2b0 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -1,12 +1,13 @@
 parameters:
 	level: 6
-	
+	checkNullables: true # level 8
+
 	ignoreErrors:
 		# need to fix
 		- "~^Function Adminer\\\\fields_from_edit\\(\\) should return~" # Mongo and SimpleDB
 		- "~Adminer\\\\Result.*mysqli_result~" # mysqli_result
 		- "~expects array~" # different shape of array
-		
+
 		# not real problems
 		- identifier: include.fileNotFound # relative includes
 		- identifier: includeOnce.fileNotFound # ./adminer-plugins.php
@@ -39,12 +40,13 @@ parameters:
 		- identifier: while.alwaysTrue
 		- identifier: isset.offset
 		- identifier: deadCode.unreachable
-		
+
 	paths:
 		- adminer/
 	scanFiles:
 		- compile.php # compile_file()
 	excludePaths:
+		- adminer/adminer-plugins.php
 		- adminer/designs.php
 		- adminer/elastic.php
 		- adminer/sqlite.php
@@ -52,11 +54,11 @@ parameters:
 		- adminer/drivers/oracle.inc.php
 		- adminer/drivers/pgsql.inc.php
 		- adminer/drivers/sqlite.inc.php
-	
+
 	phpVersion:
 		min: 70100
 		max: 80499
-		
+
 	typeAliases:
 		TableStatus: "array{Name:string, Engine?:?string, Comment?:string, Oid?:numeric-string, Rows?:?numeric-string, Collation?:string, Auto_increment?:?numeric-string, Data_length?:numeric-string, Index_length?:numeric-string, Data_free?:numeric-string, Create_options?:string, nspname?:string}"
 		Field: "array{field:?string, full_type:string, type:string, length:numeric-string, unsigned:string, default:?string, null:bool, auto_increment:bool, collation:string, privileges:int[], comment:string, primary:bool, generated:string, orig?:string, on_update:?string, on_delete?:string, inout?:string}"