remove sketchy LikelyFalse error

This error would trigger on `l:0` on the basis that this is equivalent
to `u:0` but always less efficient. There are no other "linting" errors
like this in this library, and the C++ implementation doesn't have it,
so we should drop it.

Author: apoelstra

src/lib.rs

@@ -442,8 +442,6 @@ pub enum Error {
     MultiAt(String),
     /// Name of a fragment contained `@` but we were not parsing an OR
     AtOutsideOr(String),
-    /// Encountered a `l:0` which is syntactically equal to `u:0` except stupid
-    LikelyFalse,
     /// Encountered a wrapping character that we don't recognize
     UnknownWrapper(char),
     /// Parsed a miniscript and the result was not of type T
@@ -526,7 +524,6 @@ impl fmt::Display for Error {
             Error::MultiColon(ref s) => write!(f, "«{}» has multiple instances of «:»", s),
             Error::MultiAt(ref s) => write!(f, "«{}» has multiple instances of «@»", s),
             Error::AtOutsideOr(ref s) => write!(f, "«{}» contains «@» in non-or() context", s),
-            Error::LikelyFalse => write!(f, "0 is not very likely (use «u:0»)"),
             Error::UnknownWrapper(ch) => write!(f, "unknown wrapper «{}:»", ch),
             Error::NonTopLevel(ref s) => write!(f, "non-T miniscript: {}", s),
             Error::Trailing(ref s) => write!(f, "trailing tokens: {}", s),
@@ -599,7 +596,6 @@ impl error::Error for Error {
             | MultiColon(_)
             | MultiAt(_)
             | AtOutsideOr(_)
-            | LikelyFalse
             | UnknownWrapper(_)
             | NonTopLevel(_)
             | Trailing(_)

src/miniscript/astelem.rs

@@ -412,9 +412,6 @@ impl_from_tree!(
                     )
                 }
                 'l' => {
-                    if ms.node == Terminal::False {
-                        return Err(Error::LikelyFalse);
-                    }
                     unwrapped = Terminal::OrI(
                         Arc::new(Miniscript::from_ast(Terminal::False)?),
                         Arc::new(ms),