Fix CID 1164569 (Dereference after null check) (#1332)
Fix CID 1164569 (Dereference after null check) (#1332)

If equ_detect_ can be NULL, we must catch that case and show a warning
instead of crashing in method SetEquationDetect.

Signed-off-by: Stefan Weil <8d4c780fcfdc41841e5070f4c43da8958ba6aec0@weilnetz.de>
jbarlow83/tesseract,tesseract-ocr/tesseract,jbarlow83/tesseract,jbarlow83/tesseract,tesseract-ocr/tesseract,tesseract-ocr/tesseract,UB-Mannheim/tesseract,stweil/tesseract,stweil/tesseract,UB-Mannheim/tesseract,UB-Mannheim/tesseract,amitdo/tesseract,amitdo/tesseract,amitdo/tesseract,jbarlow83/tesseract,stweil/tesseract,jbarlow83/tesseract,amitdo/tesseract,tesseract-ocr/tesseract,UB-Mannheim/tesseract,stweil/tesseract,stweil/tesseract,UB-Mannheim/tesseract,tesseract-ocr/tesseract,amitdo/tesseract