IndexError constructor Null safety
Creates a new IndexError stating that invalidValue is not a valid index
into indexable.
The length is the length of indexable at the time of the error.
If length is omitted, it defaults to indexable.length.
The message is used as part of the string representation of the error.
Implementation
IndexError(int invalidValue, dynamic indexable,
[String? name, String? message, int? length])
: this.indexable = indexable,
this.length = length ?? indexable.length,
super.value(invalidValue, name, message ?? "Index out of range");