Apply the change suggested by umezawa

optuna_dashboard/ts/components/TrialTable.tsx

@@ -92,13 +92,16 @@ export const TrialTable: FC<{
     studyDetail?.intersection_search_space.length
   studyDetail?.union_search_space.forEach((s) => {
     const sortable = s.distribution.type !== "CategoricalDistribution"
-    const filterChoices =
+    const filterChoices: (string | null)[] | undefined =
       s.distribution.type === "CategoricalDistribution"
         ? s.distribution.choices.map((c) => c.value)
         : undefined
-    const filterChoicesWithNull: (string | null)[] | undefined = filterChoices
-      ? [...filterChoices, null]
-      : undefined
+    const hasMissingValue = trials.some(
+      (t) => !t.params.some((p) => p.name === s.name)
+    )
+    if (filterChoices !== undefined && isDynamicSpace && hasMissingValue) {
+      filterChoices.push(null)
+    }
     columns.push({
       field: "params",
       label: `Param ${s.name}`,
@@ -106,7 +109,7 @@ export const TrialTable: FC<{
         trials[i].params.find((p) => p.name === s.name)?.param_external_value ||
         null,
       sortable: sortable,
-      filterChoices: isDynamicSpace ? filterChoicesWithNull : filterChoices,
+      filterChoices: filterChoices,
       // eslint-disable-next-line @typescript-eslint/no-unused-vars
       less: (firstEl, secondEl, _): number => {
         const firstVal = firstEl.params.find(