Fix wrong check from #901 (#903)

Author: Jean85

src/Credentials/WebIdentityProvider.php

@@ -128,14 +128,18 @@ private function getCredentialsFromRole(string $roleArn, string $tokenFile, ?str
      */
     private function getTokenFileContent(string $tokenFile): string
     {
-        if (!file_exists($tokenFile)) {
-            $tokenDir = \dirname($tokenFile);
-            $tokenLink = readlink($tokenFile);
-            clearstatcache(true, $tokenDir . \DIRECTORY_SEPARATOR . $tokenLink);
-            clearstatcache(true, $tokenDir . \DIRECTORY_SEPARATOR . \dirname($tokenLink));
-            clearstatcache(true, $tokenFile);
+        $token = @file_get_contents($tokenFile);
+
+        if (false !== $token) {
+            return $token;
         }
 
+        $tokenDir = \dirname($tokenFile);
+        $tokenLink = readlink($tokenFile);
+        clearstatcache(true, $tokenDir . \DIRECTORY_SEPARATOR . $tokenLink);
+        clearstatcache(true, $tokenDir . \DIRECTORY_SEPARATOR . \dirname($tokenLink));
+        clearstatcache(true, $tokenFile);
+
         if (false === $token = file_get_contents($tokenFile)) {
             throw new RuntimeException('Failed to read data');
         }