Improve calendar nav for in-between days

Did nothing in this case previously

aleksis/apps/alsijil/frontend/components/coursebook/Coursebook.vue

@@ -333,11 +333,16 @@ export default {
         // Also intersect handler does not always react to scrollIntoView
         this.setDate(date);
         present.focus("smooth");
-      } else if (
-        !this.findPrev(DateTime.fromISO(date)) ||
-        !this.findNext(DateTime.fromISO(date))
-      ) {
-        this.resetDate(date);
+      } else {
+        const prev = this.findPrev(DateTime.fromISO(date));
+        const next = this.findNext(DateTime.fromISO(date));
+        if (prev && next) {
+          // In between two present days -> goto prev
+          this.gotoDate(prev.toISODate());
+        } else {
+          // Outsite present day range
+          this.resetDate(date);
+        }
       }
     },
     gotoPrev() {