[Fix] ensure nullish values in oneOf do not crash

Fixes #256.

Author: ljharb

__tests__/PropTypesDevelopmentReact15.js

@@ -983,6 +983,17 @@ describe('PropTypesDevelopmentReact15', () => {
       );
     });
 
+    it('does not fail when the valid types contain null or undefined', () => {
+      typeCheckFail(
+        PropTypes.oneOf([0, 'false', null, undefined]),
+        false,
+        'Warning: Failed prop type: Invalid prop `testProp` of value `false` supplied to ' +
+          '`testComponent`, expected one of [0,"false",null,null].',
+          // TODO: uncomment and fix implementation
+          // '`testComponent`, expected one of [0,"false",null,undefined].',
+      );
+    });
+
     it('should not warn for valid values', () => {
       typeCheckPass(PropTypes.oneOf(['red', 'blue']), 'red');
       typeCheckPass(PropTypes.oneOf(['red', 'blue']), 'blue');

__tests__/PropTypesDevelopmentStandalone-test.js

@@ -1057,6 +1057,17 @@ describe('PropTypesDevelopmentStandalone', () => {
       );
     });
 
+    it('does not fail when the valid types contain null or undefined', () => {
+      typeCheckFail(
+        PropTypes.oneOf([0, 'false', null, undefined]),
+        false,
+        'Warning: Failed prop type: Invalid prop `testProp` of value `false` supplied to ' +
+          '`testComponent`, expected one of [0,"false",null,null].',
+          // TODO: uncomment and fix implementation
+          // '`testComponent`, expected one of [0,"false",null,undefined].',
+      );
+    });
+
     it('should not warn for valid values', () => {
       typeCheckPass(PropTypes.oneOf(['red', 'blue']), 'red');
       typeCheckPass(PropTypes.oneOf(['red', 'blue']), 'blue');

__tests__/PropTypesProductionReact15-test.js

@@ -768,6 +768,15 @@ describe('PropTypesProductionReact15', () => {
       );
     });
 
+    it('does not fail when the valid types contain null or undefined', () => {
+      expectNoop(
+        PropTypes.oneOf([0, 'false', null, undefined]),
+        false,
+        'Warning: Failed prop type: Invalid prop `testProp` of value `false` supplied to ' +
+          '`testComponent`, expected one of [0,"false",null,undefined].',
+      );
+    });
+
     it('should not warn for valid values', () => {
       expectNoop(PropTypes.oneOf(['red', 'blue']), 'red');
       expectNoop(PropTypes.oneOf(['red', 'blue']), 'blue');

factoryWithTypeCheckers.js

@@ -326,7 +326,8 @@ module.exports = function(isValidElement, throwOnDirectAccess) {
       }
 
       var valuesString = JSON.stringify(expectedValues, function replacer(key, value) {
-        if (getPropType(value) === 'symbol') {
+        var type = getPreciseType(value);
+        if (type === 'symbol') {
           return String(value);
         }
         return value;
@@ -504,6 +505,11 @@ module.exports = function(isValidElement, throwOnDirectAccess) {
       return true;
     }
 
+    // falsy value can't be a Symbol
+    if (!propValue) {
+      return false;
+    }
+
     // 19.4.3.5 Symbol.prototype[@@toStringTag] === 'Symbol'
     if (propValue['@@toStringTag'] === 'Symbol') {
       return true;