### 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
private static final EsqlParser parser = new EsqlParser();
    private final Analyzer defaultAnalyzer = AnalyzerTestUtils.expandedDefaultAnalyzer();
    public void testIncompatibleTypesInMathOperation() {
        assertEquals(
            "1:40: second argument of [a + c] must be [numeric], found value [c] type [keyword]",
            error("row a = 1, b = 2, c = \"xxx\" | eval y = a + c")
        );
        assertEquals(
            "1:40: second argument of [a - c] must be [numeric], found value [c] type [keyword]",
            error("row a = 1, b = 2, c = \"xxx\" | eval y = a - c")
        );
    }
    public void testRoundFunctionInvalidInputs() {
        assertEquals(
            "1:31: first argument of [round(b, 3)] must be [numeric], found value [b] type [keyword]",
            error("row a = 1, b = \"c\" | eval x = round(b, 3)")
        );