Fix false positive shadowing

- Don’t `registerDeclaration` on functions that aren’t `FunctionDeclaration`s.
- Added sibling function fixture

Author: wcjohnson

src/index.js

@@ -1078,8 +1078,12 @@ export default function (babel) {
             addImplicitReturns(path);
           }
 
-          // somehow this wasn't being done... may signal deeper issues...
-          path.getFunctionParent().scope.registerDeclaration(path);
+          // As this is an exit visitor, other LSC transforms have reduced
+          // arrows to plain FunctionDeclarations by this point.
+          if (path.node.type === "FunctionDeclaration") {
+            // somehow this wasn't being done... may signal deeper issues...
+            path.getFunctionParent().scope.registerDeclaration(path);
+          }
         }
       },
 

test/fixtures/variables/shadow-sibling-function/actual.js

@@ -0,0 +1,6 @@
+f = (x) -> x
+
+g(x) -> x
+
+h() ->
+  x = 3

test/fixtures/variables/shadow-sibling-function/expected.js

@@ -0,0 +1,11 @@
+const f = function (x) {
+  return x;
+};
+function g(x) {
+  return x;
+}
+
+function h() {
+  const x = 3;
+  return x;
+}