Segfault when adding widget to child of layout that has not been laid out yet

[rmacqueen]

I have a frame as a child of a constraint layout. If I try to add a Gtk.Image to that frame, then I often (4 times out of 5) get a segfault.

Traceback from running under gdb:

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7542fe5 in g_slice_alloc () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
(gdb) bt
#0  0x00007ffff7542fe5 in g_slice_alloc () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#1  0x00007ffff754361e in g_slice_alloc0 () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fffbc553484 in variable_new (solver=0xbd4730, type=VARIABLE_DUMMY) at ../src/emeus-expression.c:71
#3  0x00007fffbc557398 in simplex_solver_new_expression (solver=0xbd4730, constraint=0x15232d0, eplus_p=0x7ffffffec5f8, eminus_p=0x7ffffffec600, 
    prev_constant_p=0x7ffffffec608) at ../src/emeus-simplex-solver.c:998
#4  0x00007fffbc558543 in simplex_solver_add_constraint_internal (solver=0xbd4730, constraint=0x15232d0) at ../src/emeus-simplex-solver.c:1466
#5  0x00007fffbc558911 in simplex_solver_add_constraint (solver=0xbd4730, variable=0x148b5c0, op=OPERATOR_TYPE_EQ, expression=0x15fca70, 
    strength=1001001000) at ../src/emeus-simplex-solver.c:1568
#6  0x00007fffbc550cd4 in create_child_constraint (layout=0xbd4700, child=0xdd9ba0, constraint=0x171d350) at ../src/emeus-constraint-layout.c:1437
#7  0x00007fffbc550de4 in add_child_constraint (layout=0xbd4700, child=0xdd9ba0, constraint=0x171d350) at ../src/emeus-constraint-layout.c:1468
#8  0x00007fffbc5513b2 in layout_add_constraint (layout=0xbd4700, constraint=0x171d350) at ../src/emeus-constraint-layout.c:1614
#9  0x00007fffbc55142f in emeus_constraint_layout_add_constraint (layout=0xbd4700, constraint=0x171d350) at ../src/emeus-constraint-layout.c:1633
#10 0x00007ffff5e9cba0 in ffi_call_unix64 () from /lib/x86_64-linux-gnu/libffi.so.6
#11 0x00007ffff5e9c608 in ffi_call () from /lib/x86_64-linux-gnu/libffi.so.6
#12 0x00007ffff72557b0 in ?? () from /lib/libgjs.so.0
#13 0x00007ffff7256c4e in ?? () from /lib/libgjs.so.0
#14 0x00007ffff48472c8 in ?? () from /lib/x86_64-linux-gnu/libmozjs-31.so.0
#15 0x00007ffff48573f1 in ?? () from /lib/x86_64-linux-gnu/libmozjs-31.so.0
#16 0x00007ffff4558cb7 in ?? () from /lib/x86_64-linux-gnu/libmozjs-31.so.0