Inference through conditional expressions

lib/runtime/dart/_js_helper.js

 var _js_helper;
 (function(exports) {
   'use strict';
   class NoSideEffects extends core.Object {
     NoSideEffects() {
     }
   }
   class NoThrows extends core.Object {
     NoThrows() {
     }
@@ skipping 2403 matching lines @@
       return dart.as(TypeErrorDecoder.extractPattern(TypeErrorDecoder.provokePropertyErrorOn(void 0)), TypeErrorDecoder);
     },
     get undefinedLiteralPropertyPattern() {
       return dart.as(TypeErrorDecoder.extractPattern(TypeErrorDecoder.provokePropertyErrorOnUndefined()), TypeErrorDecoder);
     }
   });
   let _message = Symbol('_message');
   class NullError extends core.Error {
     NullError(message, match) {
       this[_message] = message;
-      this[_method] = dart.as(match == null ? null : match.method, core.String);
+      this[_method] = match == null ? null : dart.as(match.method, core.String);
       super.Error();
     }
     toString() {
       if (this[_method] == null)
         return `NullError: ${this[_message]}`;
       return `NullError: Cannot call "${this[_method]}" on null`;
     }
   }
   NullError[dart.implements] = () => [core.NoSuchMethodError];
   class JsNoSuchMethodError extends core.Error {
     JsNoSuchMethodError(message, match) {
       this[_message] = message;
-      this[_method] = dart.as(match == null ? null : match.method, core.String);
-      this[_receiver] = dart.as(match == null ? null : match.receiver, core.String);
+      this[_method] = match == null ? null : dart.as(match.method, core.String);
+      this[_receiver] = match == null ? null : dart.as(match.receiver, core.String);
       super.Error();
     }
     toString() {
       if (this[_method] == null)
         return `NoSuchMethodError: ${this[_message]}`;
       if (this[_receiver] == null) {
         return `NoSuchMethodError: Cannot call "${this[_method]}" (${this[_message]})`;
       }
       return `NoSuchMethodError: Cannot call "${this[_method]}" on "${this[_receiver]}" ` + `(${this[_message]})`;
     }
@@ skipping 61 matching lines @@
       let undefProperty = TypeErrorDecoder.undefinedPropertyPattern;
       let undefLiteralProperty = TypeErrorDecoder.undefinedLiteralPropertyPattern;
       if ((match = dart.dsend(nsme, 'matchTypeError', message)) != null) {
         return saveStackTrace(new JsNoSuchMethodError(dart.as(message, core.String), match));
       } else if ((match = dart.dsend(notClosure, 'matchTypeError', message)) != null) {
         match.method = "call";
         return saveStackTrace(new JsNoSuchMethodError(dart.as(message, core.String), match));
       } else if (dart.notNull((match = dart.dsend(nullCall, 'matchTypeError', message)) != null) || dart.notNull((match = dart.dsend(nullLiteralCall, 'matchTypeError', message)) != null) || dart.notNull((match = dart.dsend(undefCall, 'matchTypeError', message)) != null) || dart.notNull((match = dart.dsend(undefLiteralCall, 'matchTypeError', message)) != null) || dart.notNull((match = dart.dsend(nullProperty, 'matchTypeError', message)) != null) || dart.notNull((match = dart.dsend(nullLiteralCall, 'matchTypeError', message)) != null) || dart.notNull((match = dart.dsend(undefProperty, 'matchTypeError', message)) != null) || dart.notNull((match = dart.dsend(undefLiteralProperty, 'matchTypeError', message)) != null)) {
         return saveStackTrace(new NullError(dart.as(message, core.String), match));
       }
-      return saveStackTrace(new UnknownJsTypeError(dart.as(typeof message == 'string' ? message : '', core.String)));
+      return saveStackTrace(new UnknownJsTypeError(typeof message == 'string' ? dart.as(message, core.String) : ''));
     }
     if (ex instanceof RangeError) {
       if (typeof message == 'string' && dart.notNull(contains(dart.as(message, core.String), 'call stack'))) {
         return new core.StackOverflowError();
       }
       return saveStackTrace(new core.ArgumentError());
     }
     if (typeof InternalError == "function" && ex instanceof InternalError) {
       if (typeof message == 'string' && dart.notNull(dart.equals(message, 'too much recursion'))) {
         return new core.StackOverflowError();
@@ skipping 1546 matching lines @@
   exports.jsonEncodeNative = jsonEncodeNative;
   exports.getIsolateAffinityTag = getIsolateAffinityTag;
   exports.LoadLibraryFunctionType = LoadLibraryFunctionType;
   exports.DeferredLoadCallback = DeferredLoadCallback;
   exports.loadDeferredLibrary = loadDeferredLibrary;
   exports.MainError = MainError;
   exports.missingMain = missingMain;
   exports.badMain = badMain;
   exports.mainHasTooManyParameters = mainHasTooManyParameters;
 })(_js_helper || (_js_helper = {}));