Caught exception in ICat

Caught unhandled exception in ICat caused by inputing a date in an invalid format

Re #18529

qt/widgets/common/src/CatalogHelper.cpp

@@ -217,6 +217,20 @@ const std::map<std::string, std::string> CatalogHelper::validateProperties(
       // value.
       errors.emplace(iter->first + "_err", documentation);
     }
+
+  }
+ //catch invalid date formats
+  std::string dateField ="StartDate";
+  try{
+
+	  getTimevalue(catalogAlgorithm->getProperty(dateField));
+	  dateField="EndDate";
+
+	  getTimevalue(catalogAlgorithm->getProperty(dateField));
+  }catch(std::invalid_argument){
+	  std::string documentation =
+	            propertyDocumentation(catalogAlgorithm->getProperties(), dateField);
+	  errors.emplace(dateField+ "_err", documentation);
   }
   return errors;
 }
@@ -238,7 +252,10 @@ time_t CatalogHelper::getTimevalue(const std::string &inputDate) {
   std::string isoDate = dateSegments.at(2) + "-" + dateSegments.at(1) + "-" +
                         dateSegments.at(0) + " 00:00:00.000";
   // Return the date as time_t value.
+  //temp change once asked how to handle
+
   return Mantid::Types::Core::DateAndTime(isoDate).to_time_t();
+
 }
 
 /**