Fix Psalm issues after upgrade to 6

Author: trowski

src/SqlConfig.php

@@ -43,12 +43,12 @@ protected static function parseConnectionString(string $connectionString, array
             throw new \ValueError("Empty connection string");
         }
 
-        if (!\preg_match_all(
-            self::KEY_VALUE_PAIR_REGEXP,
-            $connectionString,
-            $matches,
+        if (\preg_match_all(
+            pattern: self::KEY_VALUE_PAIR_REGEXP,
+            subject: $connectionString,
+            matches: $matches,
             flags: \PREG_SET_ORDER | \PREG_UNMATCHED_AS_NULL,
-        )) {
+        ) === false) {
             throw new \ValueError("Invalid connection string");
         }
 
@@ -64,13 +64,15 @@ protected static function parseConnectionString(string $connectionString, array
                 }
             }
 
+            \assert($key !== null && $key !== '');
             $key = $keymap[$key] ?? $key;
             if (\array_key_exists($key, $values)) {
                 throw new \ValueError("Duplicate connection string key '{$key}'");
             }
 
             $values[$key] = $value;
 
+            \assert($pair !== null);
             $offset += \strlen($pair);
         }