diff --git a/js/algorithm.js b/js/algorithm.js
index 9401509..b7bddfe 100644
--- a/js/algorithm.js
+++ b/js/algorithm.js
@@ -37,7 +37,7 @@ function isEligible(employee, isoDate, monthAssignments, allHistory) {
     if (count >= c.maxPerMonth) return false;
   }
 
-  if (c.minGapDays > 0) {
+  if (c.minGapDays != null && c.minGapDays > 0) {
     // Latest prior assignment date for this employee — single pass, no sort/alloc
     let lastDate = null;
     const isLater = a => a.employeeId === employee.id && a.date < isoDate &&
diff --git a/js/app.js b/js/app.js
index e5b1ca3..db0463f 100644
--- a/js/app.js
+++ b/js/app.js
@@ -26,8 +26,9 @@ try {
       state.settings = { moderatorsPerDay: parsed.settings.moderatorsPerDay };
     }
   }
-} catch {
-  // Corrupt storage — start fresh
+} catch (e) {
+  // Corrupt storage — start fresh, but leave a breadcrumb for debugging
+  console.warn('Gespeicherter Zustand konnte nicht gelesen werden, starte leer:', e);
 }
 
 // Persist immediately. Used by the debounced saveState and the flush handlers.
diff --git a/js/calendar.js b/js/calendar.js
index bee6e4e..27b4924 100644
--- a/js/calendar.js
+++ b/js/calendar.js
@@ -99,13 +99,13 @@ export function renderCalendar() {
   renderGrid(wrapper, exportBtn);
 
   monthSel.addEventListener('change', () => {
-    currentMonth = parseInt(monthSel.value);
+    currentMonth = parseInt(monthSel.value, 10);
     loadPlanFromHistory();
     renderGrid(wrapper, exportBtn);
   });
 
   yearSel.addEventListener('change', () => {
-    currentYear = parseInt(yearSel.value);
+    currentYear = parseInt(yearSel.value, 10);
     loadPlanFromHistory();
     renderGrid(wrapper, exportBtn);
   });
diff --git a/js/employees.js b/js/employees.js
index 94bf31d..9def871 100644
--- a/js/employees.js
+++ b/js/employees.js
@@ -54,7 +54,8 @@ export function renderEmployees() {
     if (!name) return;
     try {
       state.employees.push(createEmployee(name));
-    } catch {
+    } catch (err) {
+      console.warn('Mitarbeiter konnte nicht angelegt werden:', err);
       return;
     }
     nameInput.value = '';