Allow Psalm 6 and fix newly detected errors

Author: weirdan

composer.json

@@ -25,7 +25,7 @@
     },
     "require-dev": {
         "squizlabs/php_codesniffer": "^3.4",
-        "vimeo/psalm": "^4.17.0 || dev-master || ^5.0.0 || dev-master",
+        "vimeo/psalm": "^4.17.0 || dev-master || ^5.0.0 || ^6.0.0 || dev-master",
         "phpunit/phpunit": "^9.5.20",
         "codeception/codeception": "^4.1.31 || ^5.0.0-rc3"
     },

src/Module.php

@@ -28,6 +28,7 @@
 use function is_numeric;
 use function is_string;
 
+/** @api */
 class Module extends BaseModule
 {
     /** @var array<string,string> */
@@ -144,6 +145,10 @@ public function runPsalmOn(string $filename, array $options = []): void
     public function runPsalmIn(string $dir, array $options = []): void
     {
         $pwd = getcwd();
+        if (false === $pwd) {
+            throw new TestRuntimeException('Failed to get current working directory');
+        }
+
         $this->fs()->amInPath($dir);
 
         $config = $this->psalmConfig ?: self::DEFAULT_PSALM_CONFIG;
@@ -197,7 +202,11 @@ public function seeThisError(string $type, string $message): void
     private function matches(string $expected, string $actual): bool
     {
         $regexpDelimiter = '/';
-        if ($expected[0] === $regexpDelimiter && $expected[strlen($expected) - 1] === $regexpDelimiter) {
+        if (
+            $expected !== ''
+            && $expected[0] === $regexpDelimiter
+            && $expected[strlen($expected) - 1] === $regexpDelimiter
+        ) {
             $regexp = $expected;
         } else {
             $regexp = $this->convertToRegexp($expected);
@@ -319,6 +328,10 @@ public function runPsalmWithTaintAnalysis(): void
     public function runPsalmOnASingleFile(string $file): void
     {
         $pwd = getcwd();
+        if (false === $pwd) {
+            throw new TestRuntimeException('Failed to get current working directory');
+        }
+
         $this->fs()->amInPath($this->getDefaultDirectory());
 
         $config = $this->psalmConfig ?: self::DEFAULT_PSALM_CONFIG;
@@ -473,6 +486,7 @@ public function haveADependencySatisfied(string $package, string $versionConstra
         throw new SkippedTestError("This scenario requires $package to match $versionConstraint");
     }
 
+    /** @return non-empty-string */
     private function convertToRegexp(string $in): string
     {
         return '@' . str_replace('%', '.*', preg_quote($in, '@')) . '@';
@@ -552,7 +566,7 @@ private function parseErrors(): void
             return;
         }
 
-        if (empty($this->output)) {
+        if ($this->output === null || $this->output === '') {
             $this->errors = [];
             return;
         }