Invertibility of Time-Dependent Fourier Transform
I have the 2nd edition, and there the case $m=0$ is considered, so the equation reads (Eq. $(10.21)$ on p. 716)

$$x[n] = \frac{1}{2\pi w[0]}\int_0^{2\pi} X[n, \lambda)d\lambda$$

(which of course assumes $w[0]\neq 0$). This makes sense because $e^{j\lambda m}$ equals $1$ for $m=0$.