Receiveing <UNDEFINED> error for a variable that is not referenced in the line in the error?

I am receiving the following error in my buisness operation:

ERROR <Ens>ErrException: <UNDEFINED>zGo2+181^mb.MbMainOperation.1 *tSC -- - registered as '-' number - @' set pResponse = ##class(mb.MbMessageResponse).%New()'

From what I understand, the problem occurs in the generated int file mb.MbMainOperation.1 in the method zGo2, with the offset of 181 lines, and the variable in question is a local variable tSC.

However, the line where the error occurs does not refer to tSC in any way

set pResponse = ##class(mb.MbMessageResponse).%New()

I even went as far as to set the variable at the very start of the method, but the error does not go away.

What am I missing?