[SI-2894] - bugfix sorting in radius column is now alpha numerical Signed-off-by: dtheinert <dietmar.theinert@pta.de>

diff --git a/projects/grid-failure-information-app/src/app/pages/grid-failure/grid-failure-list/grid-failure-list-column-definition.ts b/projects/grid-failure-information-app/src/app/pages/grid-failure/grid-failure-list/grid-failure-list-column-definition.ts
index 4102866..d9ff356 100644
--- a/projects/grid-failure-information-app/src/app/pages/grid-failure/grid-failure-list/grid-failure-list-column-definition.ts
+++ b/projects/grid-failure-information-app/src/app/pages/grid-failure/grid-failure-list/grid-failure-list-column-definition.ts

@@ -214,7 +214,7 @@
     colId: 'radius',
     headerName: 'GridFailure.RadiusInM',
     sortable: true,
-    comparator: stringInsensitiveComparator,
+    comparator: sortAlphaNum,
     suppressMovable: true,
     filter: 'setFilterComponent',
   },

diff --git a/projects/grid-failure-information-app/src/app/shared/utility/utilityHelpers.ts b/projects/grid-failure-information-app/src/app/shared/utility/utilityHelpers.ts
index 3345c1f..3c72fd9 100644
--- a/projects/grid-failure-information-app/src/app/shared/utility/utilityHelpers.ts
+++ b/projects/grid-failure-information-app/src/app/shared/utility/utilityHelpers.ts

@@ -127,9 +127,14 @@
     firstInput = firstInput.housenumber;
     secondInput = secondInput.housenumber;
   }
+
+  if (firstInput === secondInput) return 0;
+  if (firstInput === null || (firstInput === '' && !!secondInput)) return -1; // handle ascending sorting with NULL values
+  if (secondInput === null || (secondInput === '' && !!firstInput)) return 1; // handle decending sorting with NULL values
+
   // NULL or UNDEFINED handling
-  firstInput = !firstInput ? '0' : firstInput;
-  secondInput = !secondInput ? '0' : secondInput;
+  firstInput = !firstInput ? '0' : String(firstInput);
+  secondInput = !secondInput ? '0' : String(secondInput);
 
   const removeA = /[^a-zA-Z]/g;
   const removeNumber = /[^0-9]/g;