non_bool_operand  
                  The operands of the operator '{0}' must be assignable to 'bool'.
Description
#
                    The analyzer produces this diagnostic when one of the operands of either
                    the && or || operator doesn't have the type bool.
                  
Example
#
                    The following code produces this diagnostic because a isn't a Boolean
                    value:
                  
                      dart
                      
                  int a = 3;
bool b = a || a > 1;
Common fixes
#Change the operand to a Boolean value:
                      dart
                      
                  int a = 3;
bool b = a == 0 || a > 1;