First: have you looked at the line indicated? Is it calling the indicated function correctly, or was there a braino when it was written?
Second: is the line indicated doing what you want it to do? Are you sure? Completely? Do you have a test that proves it is doing what you wanted?
If you are 100% sure that the call is correct as it stands, add a leading ampersand to the call to the subroutine to tell Perl to ignore the prototype:
# Prototype mismatch was occurring here:
&index::encode(...);
Do
not just do this to "make it go away". You may have a real problem (in fact, you almost certainly do!). Be sure you don't before you change
anything.
Seriously. I considered whether or not to tell you this because I'm not sure you're going to do the legwork to ensure it's OK.