Solve psalm issues only present in CI

Signed-off-by: George Steel <george@net-glue.co.uk>

Author: gsteel

psalm-baseline.xml

@@ -54,12 +54,6 @@
       <code>is_object($emailOrAddress)</code>
     </RedundantConditionGivenDocblockType>
   </file>
-  <file src="src/ConfigProvider.php">
-    <MixedArrayOffset occurrences="1"/>
-    <UndefinedClass occurrences="1">
-      <code>SmtpPluginManager</code>
-    </UndefinedClass>
-  </file>
   <file src="src/Header/AbstractAddressList.php">
     <DocblockTypeContradiction occurrences="1">
       <code>null === $this-&gt;addressList</code>

src/Header/AbstractAddressList.php

@@ -9,8 +9,11 @@
 
 use function array_filter;
 use function array_map;
+use function assert;
 use function idn_to_ascii;
 use function implode;
+use function is_array;
+use function is_string;
 use function preg_match;
 use function preg_match_all;
 use function preg_replace;
@@ -146,13 +149,16 @@ public function getFieldName()
      */
     protected function idnToAscii($domainName): string
     {
+        /** @psalm-var string|false $ascii */
         $ascii = idn_to_ascii($domainName, IDNA_DEFAULT, INTL_IDNA_VARIANT_UTS46, $conversionInfo);
-        if (false !== $ascii) {
+        if (is_string($ascii)) {
             return $ascii;
         }
 
         $messages = [];
-        $errors   = (int) $conversionInfo['errors'];
+        assert(is_array($conversionInfo));
+        /* @psalm-var array{errors: numeric-string} $conversionInfo */
+        $errors = (int) $conversionInfo['errors'];
 
         foreach (self::IDNA_ERROR_MAP as $flag => $message) {
             if (($flag & $errors) === $flag) {