feat($compile): throw error when directive name or factory fn is invalid

Closes: #15056
PR (#15057)

src/ng/compile.js

@@ -1087,6 +1087,7 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
    * @returns {ng.$compileProvider} Self for chaining.
    */
   this.directive = function registerDirective(name, directiveFactory) {
+    assertArg(name, 'name');
     assertNotHasOwnProperty(name, 'directive');
     if (isString(name)) {
       assertValidDirectiveName(name);

test/ng/compileSpec.js

@@ -214,6 +214,7 @@ describe('$compile', function() {
       });
       inject(function($compile) {});
     });
+
     it('should throw an exception if a directive name has leading or trailing whitespace', function() {
       module(function() {
         function assertLeadingOrTrailingWhitespaceInDirectiveName(name) {
@@ -230,6 +231,24 @@ describe('$compile', function() {
       inject(function($compile) {});
     });
 
+    it('should throw an exception if the directive name is not defined', function() {
+      module(function() {
+        expect(function() {
+          directive();
+        }).toThrowMinErr('ng','areq');
+      });
+      inject(function($compile) {});
+    });
+
+    it('should throw an exception if the directive factory is not defined', function() {
+      module(function() {
+        expect(function() {
+          directive('myDir');
+        }).toThrowMinErr('ng','areq');
+      });
+      inject(function($compile) {});
+    });
+
     it('should preserve context within declaration', function() {
       module(function() {
         directive('ff', function(log) {