fix arrow behavior

Author: eksrvb

projects/material-calendar/src/lib/calendar-panels/calendar-panels.component.html

@@ -1,6 +1,6 @@
 <div class="divbox" *ngIf="!isLoading">
     <button mat-flat-button class="slideButton"
-        *ngIf="config.switches && mode == 'monthly' && monthsBefore != 0 && monthsAfter != 0"
+        *ngIf="config.switches && mode == 'monthly' && (monthsBefore != 0 || monthsAfter != 0)"
         (click)="onMonthBackward()">
         <span class="material-icons">
             keyboard_arrow_left
@@ -10,7 +10,7 @@
         <mat-grid-list cols="{{config.calendarWeek? 8 : 7}}" rowHeight="30px">
             <mat-grid-tile colspan="{{config.calendarWeek? 8 : 7}}" rowspan="1">
                 <button mat-icon-button
-                    *ngIf="config.switches && mode == 'monthly' && monthsBefore == 0 && monthsAfter == 0"
+                    *ngIf="config.switches && mode == 'monthly' && (monthsBefore == 0 && monthsAfter == 0)"
                     (click)="onMonthBackward()">
                     <span class="material-icons">
                         keyboard_arrow_left
@@ -23,7 +23,7 @@
                 </div>
                 <span style="flex: 1 1 auto;"></span>
                 <button mat-icon-button
-                    *ngIf="config.switches && mode == 'monthly' && monthsBefore == 0 && monthsAfter == 0"
+                    *ngIf="config.switches && mode == 'monthly' && (monthsBefore == 0 && monthsAfter == 0)"
                     (click)="onMonthForward()">
                     <span class="material-icons">
                         keyboard_arrow_right
@@ -58,7 +58,7 @@
         </mat-grid-list>
     </div>
     <button mat-flat-button class="slideButton"
-        *ngIf="config.switches && mode == 'monthly' && monthsBefore != 0 && monthsAfter != 0"
+        *ngIf="config.switches && mode == 'monthly' && (monthsBefore != 0 || monthsAfter != 0)"
         (click)="onMonthForward()">
         <span class="material-icons">
             keyboard_arrow_right