Handle else block without body (#155)

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

src/parser.rs

@@ -1426,7 +1426,21 @@ impl<'source> Parser<'source> {
                         "expected assignment or query after `else`",
                     ));
                 }
-                _ => break,
+                _ => {
+                    let mut query_span = span.clone();
+                    query_span.end = query_span.start;
+                    let query = Ref::new(Query {
+                        span: query_span,
+                        stmts: vec![],
+                    });
+                    span.end = self.end;
+                    bodies.push(RuleBody {
+                        span,
+                        assign,
+                        query,
+                    });
+                    break;
+                }
             }
         }
         Ok(())

tests/interpreter/cases/rule/else.yaml

@@ -0,0 +1,18 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
+cases:
+  - note: else without body
+    data: {}
+    modules:
+      - |
+        package test
+        x = 4 {
+          false
+        } else = 5
+
+        y = 6
+    query: data.test
+    want_result:
+      x: 5
+      y: 6