The facts.
1. It is absolutely not possible for any code inside an IF structure to run, if the condition is not met.If you do not believe this to be the case, I suggest a career in the fast food industry.
2. The enhancement is in TRINT_CORR_INSERT
3. TRINT_CORR_INSERT is not run when you start SE38, SE37 or other transactions, nor when you enter the editor.
4. The problem suddenly started happening
5. The dump can only happen if some function module is called with incorrect type at runtime.
Conclusion
1. Someone has modified some code in an important part of the system, that is executed frequently by all users.
2. The modification is somewhere other than in function module TRINT_CORR_INSERT.
3. The problem is not to do with your enhancement
Without seeing the dump ,I can't say more.