Snowflake Create Procedure returns "Syntax error: unexpected 'variableName'" when trying to use variable in an IF statement

I have the following stored procedure which I am trying to create in Snowflake new console.

CREATE OR REPLACE PROCEDURE _PTEST(ip VARCHAR)
RETURNS STRING
LANGUAGE SQL
AS
BEGIN
    -- initialize the temporary table
    CREATE OR REPLACE TEMPORARY TABLE _temp_products (Product VARCHAR);
    
    -- check which value is passed and populate the table accordingly
    IF ip = 'All' THEN
        INSERT INTO _temp_products (Product) VALUES ('value1'), ('value2'), ('value3');
        RETURN 'All';
    ELSE
        INSERT INTO _temp_products (Product) VALUES (ip);
        RETURN ip;
    END IF;
END;

When I try to execute the code I get the follwoing error

Screensot of the error

I have all the authorization as a role and I am writing in the correct database and schema.
Why do I get this error?

I also tried to put the statement in between brackets () and to pass the SQL script as string putting $$ at the beginning and at the end.

The problem seems to be linked to the fact that the variable ip is used inside the IF statement.

For example the following code works as expected:

CREATE OR REPLACE PROCEDURE _PEST2(ip VARCHAR)
RETURNS STRING
LANGUAGE SQL
AS
BEGIN
    RETURN ip;
END;

and this can be called with

CALL _PTEST2('pippo');

Two things need to be fixed :

In SQL statement the argument is specified as :ip

IF ip = 'All' THEN should be IF (ip = 'All') THEN

CREATE OR REPLACE PROCEDURE _PTEST(ip VARCHAR)
RETURNS STRING
LANGUAGE SQL
AS
BEGIN
    -- initialize the temporary table
    CREATE OR REPLACE TEMPORARY TABLE _temp_products (Product VARCHAR);
    
    IF (ip = 'All') THEN
        INSERT INTO _temp_products (Product) VALUES ('value1'), ('value2'), ('value3');
        RETURN 'All';
    ELSE
        INSERT INTO _temp_products (Product) VALUES (:ip);
        RETURN ip;
    END IF;
END;