Fix regression in blocks returning a path

Author: nicklockwood

ShapeScript/Interpreter.swift

@@ -935,8 +935,8 @@ extension EvaluationContext {
                 children.append(.point(v.transformed(by: childTransform)))
             case let .path(path):
                 children.append(.path(path.transformed(by: childTransform)))
-            case let .tuple(values) where values.isEmpty:
-                break
+            case let .tuple(values) where values.count <= 1:
+                children += values
             default:
                 children.append(value)
             }

ShapeScriptTests/InterpreterTests.swift

@@ -1401,6 +1401,18 @@ class InterpreterTests: XCTestCase {
         XCTAssertEqual(context.children.count, 1)
     }
 
+    func testBlockReturningPathInsidePath() throws {
+        let program = try parse("""
+        define foo path {
+            point 0 0
+            point 1 0
+            point 1 1
+        }
+        path { foo }
+        """)
+        XCTAssertNoThrow(try evaluate(program, delegate: nil))
+    }
+
     // MARK: Ranges
 
     func testRange() {