This ticket is the same of
GROOVY-9126 but for a different groovy version.
From the above ticket:
Starting with Groovy 2.5.5, unreachable line numbers were added to the byte code. This causes tools like JaCoCo
to report uncovered lines. Removing these line numbers after the ARETURN would be helpful.
LINENUMBER 16 L1 <-- new line number that cant be hit after ARETURN
FRAME FULL  [java/lang/Throwable]
LOCALVARIABLE this Lcom/company/Form; L0 L1 0
MAXSTACK = 2
MAXLOCALS = 1
The problem is that the bug has been introduced in
GROOVY-7647 that belongs to the changelog of 2.4.16 and the fix has been only applied to versions > 2_5_X as stated in this comment.
Please fix also versions >= 2.4.16