### Description

`stats x = count`  throws error `unknown column [count]` which is confusing since stats does not allow aliasing for existing columns but only points to aggregate functions.
Hence why the message should be `incorrect function declaration count, you forgot to add the parantheisis`. 
Same approach when dealing with a typo: `stats x = cont(*)` - `Unkown aggregate function cont - did you mean count()?`

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/analysis/VerifierTests.java
public void testSumOnDate() {
        assertEquals(
            "1:19: argument of [sum(hire_date)] must be [numeric], found value [hire_date] type [datetime]",
            error("from test | stats sum(hire_date)")
        );
    }
    public void testWrongInputParam() {
        assertEquals(
            "1:19: first argument of [emp_no == ?] is [numeric] so second argument must also be [numeric] but was [keyword]",
            error("from test | where emp_no == ?", "foo")
        );
        assertEquals(
            "1:19: first argument of [emp_no == ?] is [numeric] so second argument must also be [numeric] but was [null]",
            error("from test | where emp_no == ?", new Object[] { null })
        );
    }
    public void testPeriodAndDurationInRowAssignment() {
        for (var unit : List.of("millisecond", "second", "minute", "hour", "day", "week", "month", "year")) {
            assertEquals("1:5: cannot use [1 " + unit + "] directly in a row assignment", error("row a = 1 " + unit));
        }
    }
    public void testSubtractDateTimeFromTemporal() {
        for (var unit : List.of("millisecond", "second", "minute", "hour")) {
            assertEquals(
                "1:5: [-] arguments are in unsupported order: cannot subtract a [DATETIME] value [now()] from a [TIME_DURATION] amount [1 "
                    + unit
                    + "]",
                error("row 1 " + unit + " - now() ")
            );
        }