I get this same error in my pwdefint() function in pw.mac. I don't think it is a problem with pwdefint(). See the second case.

(%i1) pwdefint(%pi*exp(-2*%pi*abs(t))*exp(2*%pi*%i*x*t),t,minf,inf);

Maxima encountered a Lisp error:

Unhandled kernel in tvar-lim

Automatically continuing.

To reenable the Lisp debugger set *debugger-hook* to nil.

case 2:

(%i1) integrate(%pi*exp(-2*%pi*abs(t))*exp(2*%pi*%i*x*t),t,minf,inf);

Maxima encountered a Lisp error:

Unhandled kernel in tvar-lim

Automatically continuing.

To reenable the Lisp debugger set *debugger-hook* to nil.

(%i2) load(abs_integrate);

(%o2) C:/Maxima-5.18.1/share/maxima/5.18.1/share/contrib/integration/abs_integrate.mac

(%i3) integrate(%pi*exp(-2*%pi*abs(t))*exp(2*%pi*%i*x*t),t,minf,inf);

Maxima encountered a Lisp error:

Unhandled kernel in tvar-lim

Automatically continuing.

To reenable the Lisp debugger set *debugger-hook* to nil.

(%i4)