Issue 1259 concat

[valentinsulzer]

Description

Check that domains are not empty when doing a concatenation
Fixes #1259

Type of change

Please add a line in the relevant section of CHANGELOG.md to document the change (include PR #) - note reverse order of PR #s. If necessary, also add to the list of breaking changes.

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist:

• No style issues: $ flake8
• All tests pass: $ python run-tests.py --unit
• The documentation builds: $ cd docs and then $ make clean; make html

You can run all three at once, using $ python run-tests.py --quick.

Further checks:

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[valentinsulzer]

Converting to draft until #1362 is done

[codecov]

Codecov Report

Merging #1368 (cbe448a) into develop (d74083d) will increase coverage by 0.10%.
The diff coverage is 97.91%.

@@             Coverage Diff             @@
##           develop    #1368      +/-   ##
===========================================
+ Coverage    98.21%   98.31%   +0.10%     
===========================================
  Files          276      276              
  Lines        15649    15625      -24     
===========================================
- Hits         15369    15362       -7     
+ Misses         280      263      -17     

Impacted Files	Coverage Δ
pybamm/discretisations/discretisation.py	99.78% <ø> (ø)
pybamm/expression_tree/broadcasts.py	100.00% <ø> (+0.79%)	⬆️
pybamm/solvers/idaklu_solver.py	91.74% <0.00%> (+4.02%)	⬆️
pybamm/expression_tree/binary_operators.py	99.61% <100.00%> (+1.12%)	⬆️
pybamm/expression_tree/concatenations.py	97.60% <100.00%> (ø)
pybamm/expression_tree/functions.py	100.00% <100.00%> (+1.00%)	⬆️
pybamm/expression_tree/symbol.py	98.03% <100.00%> (+0.54%)	⬆️
pybamm/expression_tree/unary_operators.py	100.00% <100.00%> (+0.20%)	⬆️
pybamm/spatial_methods/finite_volume.py	98.15% <100.00%> (ø)
... and 1 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update d74083d...cbe448a. Read the comment docs.