title: Compilation Issue with Angular 9.1.x
body: <p>I'm facing a very strange issue and I hope you will be able to help to figure out what is causing it.</p>
  <p>I have 1 Angular application cloned in 2 different folders on my localhost pc.</p>
  <p>each folder get a different branch
  I use WinMerge to compare the folders and only code modifications are shown as differences but applications settings (angular.json + Package.json are identical)</p>
  <p>One application is compiling with success
  The 2nd one gets tons of errors like these ones:</p>
  <pre><code>`432         point[1].reduce((comulation, current) =&gt; comulation.concat(current), [])
                       ~~~~~~
  src/app/core/core.service.ts:277:32 - error TS2339: Property 'rowIndex' does not exist on type 'unknown'.
  
  277             let row = s.rows[c.rowIndex];
                                     ~~~~~~~~
  src/app/core/core.service.ts:284:44 - error TS2345: Argument of type 'unknown' is not assignable to parameter of type 'Control'.
    Type '{}' is missing the following properties from type 'InstructionNoteControl': controlId, name, _type, isInFirstCol, and 16 more.
  
  284             row.columns = row.columns.push(c);
                                                 ~
  src/app/core/core.service.ts:319:18 - error TS2349: This expression is not callable.
    Type '{}' has no call signatures.
  
  319         point[1].reduce((comulation, current) =&gt; comulation.concat(current), [])
                       ~~~~~~
  src/app/core/core.service.ts:841:5 - error TS2322: Type 'unknown[]' is not assignable to type 'number[]'.
    Type 'unknown' is not assignable to type 'number'.
  
  841     return arr.toArray();
          ~~~~~~~~~~~~~~~~~~~~~
  src/app/store/reducers/report-manager.reducer.ts:660:45 - error TS2339: Property 'forEach' does not exist on type 'unknown'.
  
  660     state.getIn(['currentReport', 'items']).forEach((page, pageIndex) =&gt; {
                                                  ~~~~~~~
  src/app/store/reducers/report-manager.reducer.ts:716:99 - error TS2339: Property 'map' does not exist on type 'unknown'.
  
  716   on(unverifyAllSections, state =&gt; state.updateIn(['currentReport', 'items'], pages =&gt; ([...pages.map(page =&gt; ({
                                                                                                        ~~~
  src/app/store/reducers/report-manager.reducer.ts:763:10 - error TS2339: Property 'columns' does not exist on type 'unknown'.
  
  763         .columns.filter(c =&gt; c._type !== ControlModelEnum.DropZone).size;`
  </code></pre>
  <p>I saw on internet lots of posts mentioning the Unknown versus any variable types but why it would work in one application and not in the other one ?</p>
  <p>It's like if for one of the application, all &quot;unknown&quot; type are considered as &quot;any&quot; and in the second one, &quot;unknown&quot; are really unknown. As both applications are code identical and with same settings, how on earth is it possible ?</p>
  <p>Anyone would have an idea what could couse this kind of behavior ?
  Thanks in advance
  -Vince</p>