avoid_returning_null

AVOID returning null from members whose return type is bool, double, int, or num.

Functions that return primitive types such as bool, double, int, and num are generally expected to return non-nullable values. Thus, returning null where a primitive type was expected can lead to runtime exceptions.

BAD:

bool getBool() => null;
num getNum() => null;
int getInt() => null;
double getDouble() => null;

GOOD:

bool getBool() => false;
num getNum() => -1;
int getInt() => -1;
double getDouble() => -1.0;

Usage

To enable the avoid_returning_null lint, add avoid_returning_null under linter > rules in your analysis_options.yaml file:

linter:
  rules:
    - avoid_returning_null