How do you check if an include / require_once exists before you call it, I tried putting it in an error block, but PHP didn't like that.
I think file_exists() would work with some effort, however that would require the whole file path, and a relative include could not be passed into it easily.
Are there any other ways?
I believe file_exists does work with relative paths, though you could also try something along these lines...
if(!@include("script.php")) throw new Exception("Failed to include 'script.php'");
... needless to say, you may substitute the exception for any error handling method of your choosing. The idea here is that the if-statement verifies whether the file could be included, and any error messages normally outputted by include is supressed by prefixing it with @.