I have a QGis Project with five vector-layers; every layer has about 100 up to 400 features. Everything is saved in a sqlite-database.
When I take the selecting tool (Select Features by area or single click), QGis crashes in the moment when I select a single item. Sometimes the same happens when using the Node Tool in the same moment. I can't recognize a logic to reproduce this failure. I can say that it happens not so often when saving the layer and the project frequently (and switch the Toggle Editing on and off). But it appears always the same error message:
qgis.bin: geos_ts_c.cpp:3472: int GEOSCoordSeq_setOrdinate_r(GEOSContextHandle_t, geos::geom::CoordinateSequence*, unsigned int, unsigned int, double): Assertion `0 != cs' failed.
Tested in QGis 2.14 and 2.18.09 / 2.18.10