[Internal] Warn for missing brackets (facebook#2151)

* Warn for missing braces

* Overlay, too

.eslintrc

@@ -11,6 +11,7 @@
   },
   "rules": {
     "no-console": "off",
-    "strict": ["error", "global"]
+    "strict": ["error", "global"],
+    "curly": "warn"
   }
 }

packages/react-dev-utils/ansiHTML.js

@@ -82,7 +82,9 @@ function ansiHTML(txt) {
       if (color != null) {
         result += '<span style="color: #' + color + ';">' + part + '</span>';
       } else {
-        if (fg != null) console.log('Missing color mapping: ', fg);
+        if (fg != null) {
+          console.log('Missing color mapping: ', fg);
+        }
         result += '<span>' + part + '</span>';
       }
       if (_index < contentParts.length - 1) {

packages/react-error-overlay/.eslintrc

@@ -1,3 +1,6 @@
 {
-  "extends": "react-app"
+  "extends": "react-app",
+  "rules": {
+    "curly": "warn"
+  }
 }

packages/react-error-overlay/src/utils/mapper.js

@@ -17,7 +17,9 @@ async function map(
   const files: string[] = [];
   frames.forEach(frame => {
     const { fileName } = frame;
-    if (fileName == null) return;
+    if (fileName == null) {
+      return;
+    }
     if (files.indexOf(fileName) !== -1) {
       return;
     }

packages/react-error-overlay/src/utils/unmapper.js

@@ -67,7 +67,9 @@ async function unmap(
       }))
       .sort((a, b) => {
         const s = Math.sign(a.seps - b.seps);
-        if (s !== 0) return s;
+        if (s !== 0) {
+          return s;
+        }
         return Math.sign(a.penalties - b.penalties);
       });
     if (source.length < 1 || lineNumber == null) {