set_default_frame() too restrictive on parallelizable manifolds #30320
Description
sage: M = Manifold(3, 'M')
sage: U = M.open_subset('U'); V = M.open_subset('V')
sage: c_xyz.<x,y,z> = U.chart(); c_uvt.<u,v,t> = V.chart()
sage: M.default_frame()
Coordinate frame (U, (d/dx,d/dy,d/dz))
sage: e = M.vector_frame('e'); e
Vector frame (M, (e_0,e_1,e_2))
sage: M.default_frame()
Coordinate frame (U, (d/dx,d/dy,d/dz))
sage: M.set_default_frame(c_xyz.frame())
Traceback (most recent call last):
...
ValueError: the frame domain must coincide with the 3-dimensional differentiable manifold M
In case of M=SU(2)=S^3 this can happen: it cannot be covered by one chart but is parallelizable.
However, due to the error message, the method default_frame is obviously intended to return the default frame which covers M if possible. This is not given in the above example.
CC: @egourgoulhon @tscrim
Component: manifolds
Author: Michael Jung
Branch/Commit: 7f50b3d
Reviewer: Eric Gourgoulhon
Issue created by migration from https://trac.sagemath.org/ticket/30320