Added null check in equals function and updated tests.

[ScottAtRedHawk]

No description provided.

[ScottAtRedHawk]

Here is example of the use case this fixes:

void main() {
  const String? optionalStr = null;
  
  print(equals('null', optionalStr)); // true
  print(equalsNew('null', optionalStr)); // false
}

bool equals(String str, Object? comparison) {
  return str == comparison.toString();
}

bool equalsNew(String str, Object? comparison) {
  if (comparison == null) {
    // any non-nullable String will never equal null
    // this still a valid use case though
    return false;
  }
  
  return str == comparison.toString();
}

[suragch]

Good catch. Thank you for your PR!

[suragch]

Published as version 1.0.1.