[SI-2944] - correct filter handling so empty cell values will also be found

Signed-off-by: dtheinert <dietmar.theinert@pta.de>

projects/grid-failure-information-app/src/app/shared/filters/ag-grid/fuzzy-set-filter/fuzzy-set-filter.component.ts

diff --git a/projects/grid-failure-information-app/src/app/shared/filters/ag-grid/fuzzy-set-filter/fuzzy-set-filter.component.ts b/projects/grid-failure-information-app/src/app/shared/filters/ag-grid/fuzzy-set-filter/fuzzy-set-filter.component.ts
index 325a7bc..219e2aa 100644
--- a/projects/grid-failure-information-app/src/app/shared/filters/ag-grid/fuzzy-set-filter/fuzzy-set-filter.component.ts
+++ b/projects/grid-failure-information-app/src/app/shared/filters/ag-grid/fuzzy-set-filter/fuzzy-set-filter.component.ts
@@ -34,7 +34,7 @@
       } else {
         // is numeric or null
         if (!nodeValue) {
-          passed = nodeValue === null && itemKey === 'null';
+          passed = (nodeValue === null || nodeValue === '') && itemKey === 'null';
         } else {
           passed = nodeValue.toString() === itemKey;
         }