remove panics on malformed @ if

src/atrule/if_rule.rs

@@ -1,4 +1,4 @@
-use codemap::Spanned;
+use codemap::{Spanned, Span};
 
 use peekmore::{PeekMore, PeekMoreIterator};
 
@@ -35,14 +35,21 @@ impl Branch {
 impl If {
     pub fn from_tokens<I: Iterator<Item = Token>>(
         toks: &mut PeekMoreIterator<I>,
+        span_before: Span,
     ) -> SassResult<If> {
         devour_whitespace_or_comment(toks)?;
         let mut branches = Vec::new();
         let init_cond = read_until_open_curly_brace(toks);
-        toks.next();
+        if toks.next().is_none() {
+            return Err(("Expected expression.", span_before).into());
+        }
         devour_whitespace_or_comment(toks)?;
         let mut init_toks = read_until_closing_curly_brace(toks);
-        init_toks.push(toks.next().unwrap());
+        if let Some(tok) = toks.next() {
+            init_toks.push(tok);
+        } else {
+            return Err(("expected \"}\".", span_before).into())
+        }
         devour_whitespace(toks);
 
         branches.push(Branch::new(init_cond, init_toks));

src/atrule/mod.rs

@@ -216,7 +216,7 @@ impl AtRule {
                 span: kind_span,
             },
             AtRuleKind::If => Spanned {
-                node: AtRule::If(If::from_tokens(toks)?),
+                node: AtRule::If(If::from_tokens(toks, kind_span)?),
                 span: kind_span,
             },
             AtRuleKind::For => Spanned {

tests/if.rs

@@ -108,3 +108,13 @@ test!(
     "@if false {}\n\n@\\45lse {\n  a {\n    color: red;\n  }\n}\n",
     "a {\n  color: red;\n}\n"
 );
+error!(
+    nothing_after_if,
+    "@if",
+    "Error: Expected expression."
+);
+error!(
+    nothing_after_open_curly,
+    "@if foo {",
+    "Error: expected \"}\"."
+);