Undefined name in type test expressionDRT-W1652

The analyzer produces this diagnostic when the name following the is in a type test expression isn't defined.

Example

The following code produces this diagnostic because the name Srting isn't defined:

void f(Object o) {
  if (o is Srting) {
    // ...
  }
}

Common fixes

Replace the name with the name of a type:

void f(Object o) {
  if (o is String) {
    // ...
  }
}