Erro no tratamento de usuário não logado (primeiro *ngIf)

Boa tarde a todos

Efetuei a implementação da primeira parte onde caso o usuário não esteja logado a mensagem Please, login! deve ser exibida ao usuário... Vejam:

header.component.html

<header class="fixed-top">
    <nav class="navbar navbar-light bg-white">
        <a class="navbar-brand">ALURAPIC</a>
        <div *ngIf="user; else login">
            <i class="fa fa-user-circle"></i>
            <a class="ml-2"> {{ user.name }}}</a>
        </div>

        <ng-template #login>
            <span class="navbar-text">
                Favor efetue login!
            </span>
        </ng-template>

    </nav>
</header>

Ao colocar no header.component.html ngIf="user; else login" em desenvolvimento a tela da aplicação já fica branca e um erro é exibido no console...

vendor.js:8730 Uncaught Error: Template parse errors:
Can't bind to 'ngIf' since it isn't a known property of 'div'. ("v class="navbar navbar-light bg-white">
        <a class="navbar-brand">ALURAPIC</a>
        <div [ERROR ->]*ngIf="user; else login">
            <i class="fa fa-user-circle"></i>
            <a class="ml-2""): ng:///CoreModule/HeaderComponent.html@3:13
Can't bind to 'ngIfElse' since it isn't a known property of 'div'. ("v class="navbar navbar-light bg-white">
        <a class="navbar-brand">ALURAPIC</a>
        <div [ERROR ->]*ngIf="user; else login">
            <i class="fa fa-user-circle"></i>
            <a class="ml-2""): ng:///CoreModule/HeaderComponent.html@3:13
Property binding ngIf not used by any directive on an embedded template. Make sure that the property name is spelled correctly and all directives are listed in the "@NgModule.declarations". ("  <nav class="navbar navbar-light bg-white">
        <a class="navbar-brand">ALURAPIC</a>
        [ERROR ->]<div *ngIf="user; else login">
            <i class="fa fa-user-circle"></i>
            <a class=""): ng:///CoreModule/HeaderComponent.html@3:8
Property binding ngIfElse not used by any directive on an embedded template. Make sure that the property name is spelled correctly and all directives are listed in the "@NgModule.declarations". ("  <nav class="navbar navbar-light bg-white">
        <a class="navbar-brand">ALURAPIC</a>
        [ERROR ->]<div *ngIf="user; else login">
            <i class="fa fa-user-circle"></i>
            <a class=""): ng:///CoreModule/HeaderComponent.html@3:8
    at syntaxError (vendor.js:8730)
    at TemplateParser.push../node_modules/@angular/compiler/fesm5/compiler.js.TemplateParser.parse (vendor.js:23217)
    at JitCompiler.push../node_modules/@angular/compiler/fesm5/compiler.js.JitCompiler._parseTemplate (vendor.js:31224)
    at JitCompiler.push../node_modules/@angular/compiler/fesm5/compiler.js.JitCompiler._compileTemplate (vendor.js:31211)
    at vendor.js:31154
    at Set.forEach (<anonymous>)
    at JitCompiler.push../node_modules/@angular/compiler/fesm5/compiler.js.JitCompiler._compileComponents (vendor.js:31154)
    at vendor.js:31064
    at Object.then (vendor.js:8721)
    at JitCompiler.push../node_modules/@angular/compiler/fesm5/compiler.js.JitCompiler._compileModuleAndComponents (vendor.js:31063)

Sei que é complicado determinar o erro assim, mas se puderem me ajudar agradeço!

Abraço

EDUARDO AGOSTINHO