title: NoSuchMethodError, Exception caught by widgets library
body: <p>════════ Exception caught by widgets library ═══════════════════════════════════════════════════════
  The following NoSuchMethodError was thrown building Builder(dirty):
  The method '&gt;=' was called on null.
  Receiver: null
  Tried calling: &gt;=(25)</p>
  <p>The relevant error-causing widget was:
  MaterialApp file:///C:/Users/Ahmed/AndroidStudioProjects/bmi_calc/lib/main.dart:8:12
  When the exception was thrown, this was the stack:</p>
  <h1>0      Object.noSuchMethod (dart:core-patch/object_patch.dart:53:5)</h1>
  <h1>1      calculator.getresult (package:bmicalc/calculator.dart:14:14)</h1>
  <h1>2      _InputPageState.build.. (package:bmicalc/input_page.dart:226:97)</h1>
  <h1>3      MaterialPageRoute.buildPage (package:flutter/src/material/page.dart:87:27)</h1>
  <h1>4      _ModalScopeState.build. (package:flutter/src/widgets/routes.dart:710:43)</h1>
  <p>At #1 my code is</p>
  <pre><code>class calculator {
    calculator({this.height, this.weight});
    final int height;
    final int weight;
    double _bmi;
    String calculatebmi() {
      _bmi = (weight / pow(height / 100, 2));
      return _bmi.toStringAsFixed(1);
    }
  
    String getresult() {
      if (_bmi &gt;= 25) {
        return 'Overweight';
      } else if (_bmi &gt; 18.5) {
        return 'Normal';
      } else {
        return 'Underweight';
      }
      return ' ';
    }
  
    String getRemarks() {
      if (_bmi &gt;= 25) {
        return 'Your weight is more than average body weight, try to excercise.';
      } else if (_bmi &gt; 18.5) {
        return 'Your weight is normal';
      } else {
        return 'Your weight is less than average body weight, try to eat more';
      }
    }
  }
  </code></pre>
  <p>At #2</p>
  <pre><code>`GestureDetector(  
  onTap: () {
  calculator cal = calculator(height: height, weight: weight);
  Navigator.push(context, MaterialPageRoute(builder: (context) =&gt; results(result: calculator().getresult(), bmi: calculator().calculatebmi(), remarks: calculator().getRemarks())));
  },)`
  </code></pre>