title: Unrelated template parse error in Angular 6
body: <p>I am developing a simple Angular 6 application. At a certain point a 'Template parse error' appeared, literally out of nowhere: "let-" is only supported on ng-template elements. I don't use any template or ng-template in my code. Anybody with an idea?</p>
  
  <pre><code>Uncaught Error: Template parse errors:
  "let-" is only supported on ng-template elements. ("
    &lt;/thead&gt;
    &lt;tbody&gt;
      &lt;template ngFor [ngForOf]="rows" [ERROR -&gt;]let-rowz="$implicit" let-index="index"&gt;
        &lt;tr *ngIf="!(datePicker.onlyCurrentMonth &amp;&amp; rowz[0].sec"): ng:///DatepickerModule/DayPickerComponent.html@38:37
  "let-" is only supported on ng-template elements. ("
    &lt;/thead&gt;
    &lt;tbody&gt;
      &lt;template ngFor [ngForOf]="rows" let-rowz="$implicit" [ERROR -&gt;]let-index="index"&gt;
        &lt;tr *ngIf="!(datePicker.onlyCurrentMonth &amp;&amp; rowz[0].secondary &amp;&amp; rowz[6].sec"): ng:///DatepickerModule/DayPickerComponent.html@38:58
      at syntaxError (compiler.js:2547)
      at TemplateParser.push../node_modules/@angular/compiler/fesm5/compiler.js.TemplateParser.parse (compiler.js:19495)
      at JitCompiler.push../node_modules/@angular/compiler/fesm5/compiler.js.JitCompiler._parseTemplate (compiler.js:25041)
      at JitCompiler.push../node_modules/@angular/compiler/fesm5/compiler.js.JitCompiler._compileTemplate (compiler.js:25028)
      at compiler.js:24971
      at Set.forEach (&lt;anonymous&gt;)
      at JitCompiler.push../node_modules/@angular/compiler/fesm5/compiler.js.JitCompiler._compileComponents (compiler.js:24971)
      at compiler.js:24881
      at Object.then (compiler.js:2538)
      at JitCompiler.push../node_modules/@angular/compiler/fesm5/compiler.js.JitCompiler._compileModuleAndComponents (compiler.js:24880)
  </code></pre>