Differential equations – where does the 1/0 come from in this call to DSolve?

Report to the IRG[[[[CAS: 4246236]


This uses 11.3 on Windows 10.

This is a manual pde of the first-order partial differential equations
by Polyanin, Zaitsev, Moussiaux

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Mathematica 11.3 returns 1/0 immediately.

From a clean core

## EQU1 ##[w[x, y, z], X]+
a * (b * (a ^ 2 * x ^ 2 + b ^ 2 * y ^ 2 - 1) * y - a * x) * D[w[x, y, z], y]+
2 * a * b * z * D[w[x, y, z], z]== 0;

Resolution[pde, w[x, y, z], {X Y Z}]

Mathematica graphics

Why is 1/0 generated? Is this a bug?

I do not have access to 12.0, I wonder if this same error is generated in 12.0?