How to fix the work of a self-written module for Drupal?

Question

Drupal

Hello colleagues.
There was not an easy, in my opinion, task - to deal with a module that does not work correctly.
The module is self-written, the developer left, there are no comments on the code, nothing is clear.
How the module works
There is a form on the site
Form for selecting the type of activity
We select the type of activity we are interested in, labels are displayed immediately on the map
Map
Everything works correctly as long as the user has one type of activity selected
type of activity ,
but if the user has more than one type of activity selected , then its label is constantly displayed on the map, even if an activity is selected for display that the user does not have.
I understand that this information is extremely small, but I cannot provide the module code or disclose the resource on which it works.
Tell me where to start? Where to look? In what it in general can be a problem?
Thanks in advance.

Answer 1

Generally understood. Changed the query to the database and a little php. What kind of question is this and the answer ... a finger to the sky. Have a nice evening and weekend everyone

Answer 2

The module is self-written, the developer left, there are no comments on the code, nothing is clear.

The French are so French.
Start by opening the folder with the module. And see all the files that are there.
And then start debugging line by line using Xdebug.
On the other hand, if there is tied to Google maps, then you have to pick with JS.
The problem can be in anything, there the variable can no longer take on a value and that's it.
Something you absolutely frogs intimidated. Are you doing an internship? And by the way, you correctly said that without a code, alas, it’s hard to help
.