Print input line number where error occurred

[jidanni]

We see e.g.,

Data value had 16 elements expecting 1 or less. at /usr/share/perl5/Text/vCard.pm line 575. Can't call method "family" on an undefined value at /usr/share/perl5/vCard/AddressBook.pm line 208.

Please also mention what line of the input the problem occurred on. Reproduce with e.g.,

X-ANDROID-CUSTOM:vnd.android.cursor.item/nickname;1-6;;;;;;;;;;;;;;

(an arbitrary custom line, which by the way it would be great if the man page gave an example of how to deal with. (I only see "If you wish to extend this package (for custom attributes), overload ..."))