[sr-dev] [kamailio/kamailio] substr transformation error does not include config line number (#1019)

[Juha Heinanen]

Daniel-Constantin Mierla writes:

> I pushed a patch to attempt to print the line for string transformation errors, as they are commonly used. However, this can be also accomplished for all error logs by setting config parameters:
> 
> ```
> log_prefix_mode=1
> log_prefix="(cfg line: $cfg(line) "

OK, good to know, since also uri2dst2() errors don't show config line
number.

-- Juha