Ultraspherical conversion error catching

[Gyoshi]

Closes #31

[dlfivefifty]

For some reason Travis checks are not running on any repository... let me look into it

[codecov]

Codecov Report

Merging #32 into master will decrease coverage by 1.70%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #32      +/-   ##
==========================================
- Coverage   56.83%   55.13%   -1.71%     
==========================================
  Files          27       27              
  Lines        2106     2171      +65     
==========================================
  Hits         1197     1197              
- Misses        909      974      +65     

Impacted Files	Coverage Δ
...c/Spaces/Ultraspherical/UltrasphericalOperators.jl	73.64% <100.00%> (-0.51%)	⬇️
src/Spaces/Ultraspherical/DirichletSpace.jl	27.00% <0.00%> (-3.00%)	⬇️
src/ultraspherical.jl	54.92% <0.00%> (-2.43%)	⬇️
src/Spaces/Jacobi/JacobiOperators.jl	49.81% <0.00%> (-2.26%)	⬇️
src/Spaces/PolynomialSpace.jl	80.30% <0.00%> (-2.09%)	⬇️
src/Spaces/Hermite/Hermite.jl	47.94% <0.00%> (-2.06%)	⬇️
src/specialfunctions.jl	68.42% <0.00%> (-1.85%)	⬇️
src/Spaces/Jacobi/Jacobi.jl	49.41% <0.00%> (-1.81%)	⬇️
src/roots.jl	53.00% <0.00%> (-1.64%)	⬇️
src/Domains/Line.jl	23.14% <0.00%> (-1.37%)	⬇️
... and 8 more

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[dlfivefifty]

Can you add a test? (Something that fails without it but now passes.)

[Gyoshi]

I could add

@test_throws ArgumentError Conversion(Ultraspherical(2), Ultraspherical(1))
@test_throws ArgumentError Conversion(Ultraspherical(3), Ultraspherical(1.9))

but the error for 3 -> 1.9 is only there due to incomplete implementation. If it someone implements it, it shouldn't fail the tests because of that, right?

[dlfivefifty]

Those tests sound fine. Yes if they are implemented that can be changed

[dlfivefifty]

I think the test failure is unrelated, I'll merge.