title: Start to use 'strict' in tsconfig
body: <p>I have this <code>tsconfig.json</code> file</p>
  <pre class="lang-json prettyprint-override"><code>{
    &quot;compilerOptions&quot;: {
      &quot;target&quot;: &quot;es2019&quot;,
      &quot;lib&quot;: [
        &quot;es2020&quot;,
        &quot;esnext.asynciterable&quot;
      ],
      &quot;typeRoots&quot;: [
        &quot;./node_modules/@types&quot;,
        &quot;./src/types&quot;
      ],
      &quot;allowSyntheticDefaultImports&quot;: true,
      &quot;experimentalDecorators&quot;: true,
      &quot;emitDecoratorMetadata&quot;: true,
      &quot;forceConsistentCasingInFileNames&quot;: true,
      &quot;moduleResolution&quot;: &quot;node&quot;,
      &quot;module&quot;: &quot;commonjs&quot;,
      &quot;pretty&quot;: true,
      &quot;sourceMap&quot;: true,
      &quot;outDir&quot;: &quot;./build&quot;,
      &quot;allowJs&quot;: true,
      &quot;noEmit&quot;: false
    },
    &quot;include&quot;: [
      &quot;./src/**/*&quot;
    ],
    &quot;exclude&quot;: [
      &quot;node_modules&quot;,
      &quot;tests&quot;
    ]
  }
  
  </code></pre>
  <p>As far as you can see there are no strict rules there. The most important for me it's starting to use <code>strictNullChecks</code> setting, but my project is already large, and when I set this setting to <code>true</code> I've got ~1000 errors.</p>
  <p>I want to start refactor code for avoiding potential issues, but I want to move step by step, file by file and don't want to spend time resolving 1000 errors at once.</p>
  <p>How can I achieve it?
  I had a plan to use a comment <code>// @ts-ignore</code> for each error line and then incrementally resolve problems. But it's even hard to add <code>// @ts-ignore</code> 1000 times. How can I do it automatically?
  Any advice please</p>