Why does Sqlite3 let you store a String on a float?

Gentlemen,

I'm working on Sqlite3 for android, and I've seen that it allows storing a STRING in a FLOAT value, how do I control that?

I leave you the create:

 CREATE TABLE 'mercado' (  'id' INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
 'id_tienda' INTEGER NOT NULL,  'id_usuario' INTEGER NOT NULL, 'total' FLOAT NOT
 NULL, 'fecha_registro' VARCHAR(45) NOT NULL,  'estado_mercado' INTEGER NOT NULL)";

The Insert:

insert into mercado values(3,1,1,'papaya','2018-11-02',0);

The result:

Record 3 shows the error