objToVTK broken since v1812

Since v1812, objToVTK does not work.

How to reproduce:

Convert any .obj file to .vtk, e.g.:

cp -r $FOAM_TUTORIALS/incompressible/icoFoam/cavity/cavity .
cd cavity
blockMesh -blockTopology
objToVTK blockTopology.obj test.vtk # fails

Error message:

--> FOAM FATAL IO ERROR:
Bad token - could not get word

file: input at line 0.

    From function Foam::Istream& Foam::operator>>(Foam::Istream&, Foam::word&)
    in file primitives/strings/word/wordIO.C at line 48.

Versions up to (and including) v1806 work fine. v1812, v1906 and v1912 exhibit the error. The generated blockTopology.obj is the same among all versions, so the culprit seems to be objToVTK.