No compile time error when using Inner Join without On

[rkosafo]

When an inner join is written without on, it does not fail at compile time but rather give a runtime error like Incorrect syntax near ';'..

Using the default model and tsql,

module Tests =
  let print = printf "Output: %A"

  type InnerJoinWithoutOn = SQL<"""
    Select *
    From Users u
    Inner Join Comments c --ON is missing """>
  let innerJoinWithoutOn () = 
    use ctx = new ConnectionContext ()
    InnerJoinWithoutOn.Command().Execute (ctx) |> print

It will be nice if this can fail at compile time instead of at runtime.

[rspeele]

This is actually legal syntax in SQLite, but it does seem pretty pointless, so it might as well be an error on all backends.

[rspeele]

a178ba7c922f55685c40bfbdfde0f96e9921aebc should knock this one out. All joins will require "on " except comma-joins like select * from a, b, c where ....