coderisimo, в resources/views нету app.blade.php
Там метод описан:
protected function findInPaths($name, $paths)
{
foreach ((array) $paths as $path) {
foreach ($this->getPossibleViewFiles($name) as $file) {
if ($this->files->exists($viewPath = $path.'/'.$file)) {
return $viewPath;
}
}
}
throw new InvalidArgumentException("View [$name] not found.");
}