Cleaned up diagnostics

Author: rbuckton

src/compiler/checker.ts

@@ -9604,11 +9604,7 @@ namespace ts {
                     //  }
                     //
                     if (location) {
-                        if (!message) {
-                            message = Diagnostics.Operand_for_await_does_not_have_a_valid_callable_then_member;
-                        }
-                        
-                        error(location, message);
+                        error(location, Diagnostics._0_is_referenced_directly_or_indirectly_in_the_fulfillment_callback_of_its_own_then_method, symbolToString(type.symbol));
                     }
 
                     type = unknownType;
@@ -9640,8 +9636,7 @@ namespace ts {
             let globalPromiseConstructorLikeType = getGlobalPromiseConstructorLikeType();
             if (globalPromiseConstructorLikeType === emptyObjectType) {
                 // If we couldn't resolve the global PromiseConstructorLike type we cannot verify
-                // compatibility with __awaiter, so we report an error.
-                error(node, Diagnostics.An_async_function_or_method_must_have_a_valid_awaitable_return_type);
+                // compatibility with __awaiter.
                 return unknownType;
             }
 

src/compiler/diagnosticInformationMap.generated.ts

@@ -54,6 +54,7 @@ namespace ts {
         Return_expression_in_async_function_does_not_have_a_valid_callable_then_member: { code: 1059, category: DiagnosticCategory.Error, key: "Return expression in async function does not have a valid callable 'then' member." },
         Expression_body_for_async_arrow_function_does_not_have_a_valid_callable_then_member: { code: 1060, category: DiagnosticCategory.Error, key: "Expression body for async arrow function does not have a valid callable 'then' member." },
         Enum_member_must_have_initializer: { code: 1061, category: DiagnosticCategory.Error, key: "Enum member must have initializer." },
+        _0_is_referenced_directly_or_indirectly_in_the_fulfillment_callback_of_its_own_then_method: { code: 1062, category: DiagnosticCategory.Error, key: "{0} is referenced directly or indirectly in the fulfillment callback of its own 'then' method." },
         An_export_assignment_cannot_be_used_in_a_namespace: { code: 1063, category: DiagnosticCategory.Error, key: "An export assignment cannot be used in a namespace." },
         Ambient_enum_elements_can_only_have_integer_literal_initializers: { code: 1066, category: DiagnosticCategory.Error, key: "Ambient enum elements can only have integer literal initializers." },
         Unexpected_token_A_constructor_method_accessor_or_property_was_expected: { code: 1068, category: DiagnosticCategory.Error, key: "Unexpected token. A constructor, method, accessor, or property was expected." },

src/compiler/diagnosticMessages.json

@@ -203,6 +203,10 @@
         "category": "Error",
         "code": 1061
     },
+    "{0} is referenced directly or indirectly in the fulfillment callback of its own 'then' method.": {
+        "category": "Error",
+        "code": 1062
+    },
     "An export assignment cannot be used in a namespace.": {
         "category": "Error",
         "code": 1063