LPE knot: crash when joining two paths in node tool and selecting knot

[Liam P. White]

1. Create a path with a loop in it (so that the knot path effect can work correctly)
2. Duplicate it, and line up one of the ends
3. Join the two paths in the node tool

Ideally at this point, the invalid knot should just disappear and the path effect should create a new one in its place, but this might not always be plausible (or even possible).

4. Click both of the knots. Clicking one of the two will crash the program.

Backtrace attached.

(Possibly reproducible with other path effects, based on past experience. Not sure which others to test on though.)

[su_v (suv-lp)]

Reproduced with Inkscape 0.48.5 and 0.48+devel r13455 on OS X 10.7.5.

[jazzynico (jazzynico)]

Also reproduced on Windows XP, Inkscape trunk revision 13484.

[Liam P. White (liampwhite)]

Also works with "Hatches (rough)" path effect, and combinations of different path effects that also provide knots.

[Jabiertxof (jabiertxof)]

Is fixed in 0.92.x and master not sure when