BUG - Value assign to string variable

[r-koubou]

EXPECT

@str := "Hello" {OK}
@str := 0       {OK}
@str := 0.0     {OK}

NOW

@str := "Hello" {OK}
@str := 0       {NG: integer value is Invalid type}
@str := 0.0     {NG: real value is Invalid type}

Now, work in progress.