It seems there are three minor modifications to the plugin files, all having to do with avoiding the use of anonymous functions. Just for reference, anonymous functions were introduced in PHP 5.3.0 and your blog’s server is running 5.3.29. However, there must be some other variable in the server environment having trouble processing them.
General queries for “Invalid opcode 153/1/8” point to a caching utility called eAccelerator, which is not compatible with anonymous functions. Assuming your server environment is running eAccelerator, it is possible you will run into issues in the future with other plugins as the use of anonymous functions is becoming more commonplace, so changing caching solutions could be a consideration.
It may also be time to speak with your hosting provider about an upgrade to PHP. As it turns out, PHP 5.3.29 reached end of life a while back and is no longer supported. “Users of this release should upgrade as soon as possible, as they may be exposed to unpatched security vulnerabilities.”
As you can probably surmise from the minimal number of plugin modifications and their nature, the analysis of the upwork technician was a bit of an overreach to say the least. That being said, we will gladly replace the three occurrences of the anonymous functions in the RPS Image Gallery code for the next release so the next update will be a much better experience for you.
Thank you again for sticking with us through the troubleshooting and diagnosis of the issue. Please let us know if there is anything we can do in the meantime to make RPS Image Gallery work better for you.