fix category autocomplete error when no icon is present
<mat-autocomplete #auto="matAutocomplete" autoActiveFirstOption [displayWith]="categoryAutocompleteDisplay" (onCategorySelected)="categorySelected($event)" >
<mat-option *ngFor="let category of filteredCategories | async" [value]="category" class="autocomplete-option">
<span [class.disabled]="!category.createFeed">
- <ng-md-icon [icon]="category.icon" [ngStyle]="{'fill':category.iconColor}" *ngIf="category.createFeed"></ng-md-icon>
+ <ng-md-icon [icon]="category.icon" [ngStyle]="{'fill':category.iconColor}" *ngIf="category.createFeed && category.icon"></ng-md-icon>
<ng-md-icon icon="block" class="disabled" *ngIf="!category.createFeed"></ng-md-icon>
<span class="title"> {{category.name}}</span>
<br/>
