fix error when using intro and outro text

[YvarRavy]

Fixes issue: #853
i first checked how SMW handels this with broadtable and pretty much just moved this code

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 8 lines in your changes missing coverage. Please review.

Project coverage is 40.77%. Comparing base (fd72ce3) to head (c29cbf8).

Files with missing lines	Patch %	Lines
formats/datatables/DataTables.php	0.00%	8 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #854      +/-   ##
============================================
- Coverage     40.80%   40.77%   -0.04%     
- Complexity     2404     2410       +6     
============================================
  Files            81       81              
  Lines          7850     7856       +6     
============================================
  Hits           3203     3203              
- Misses         4647     4653       +6     

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[YvarRavy]

could you check this out? @gesinn-it-ilm

[gesinn-it-ilm]

@JeroenDeDauw could you please review this PR? Thanks.

[JeroenDeDauw]

Costs too many brain cycles. If another dev vouches for this code I am happy to merge

[thomas-topway-it]

I will check it soon on my side, I was also planning to do a few updates to carousel format