Merge pull request #174 from codehag/fix-118-add-error-prose

Add a section describing what happens when an error is encountered in…

spec.html

@@ -1037,6 +1037,117 @@ <h1>Example Cyclic Module Record Graphs</h1>
         </tbody>
       </table>
     </emu-table>
+
+    <p><ins>
+      Alternatively, consider a failure case where _C_ fails execution and returns an error before _B_ has finished executing. When that happens, AsyncModuleExecutionRejected is called and _C_.[[AsyncEvaluating]] is set to *false*. We then set the evaluation error of the module to the error returned by executing _C_. We then propagate this error to all of the AsyncParentModules by performing AsyncModuleExeutionRejected on each of them. The fields of the updated modules are as given in <emu-xref href="#table-module-graph-cycle-async-fields-7"></emu-xref>.
+    </ins></p>
+
+    <emu-table id="table-module-graph-cycle-async-fields-7" caption="Module fields after module _C_ finishes with an error">
+      <table>
+        <thead>
+          <tr>
+            <th>Module</th>
+            <th>[[DFSIndex]]</th>
+            <th>[[DFSAncestorIndex]]</th>
+            <th>[[AsyncEvaluating]]</th>
+            <th>[[AsyncParentModules]]</th>
+            <th>[[PendingAsyncDependencies]]</th>
+            <th>[[EvaluationError]]</th>
+          </tr>
+        </thead>
+        <tbody>
+          <tr>
+            <th>_A_</th>
+            <td>0</td>
+            <td>0</td>
+            <td>*true*</td>
+            <td>&laquo; &raquo;</td>
+            <td>1 (_B_)</td>
+            <td>~empty~</td>
+          </tr>
+          <tr>
+            <th>_C_</th>
+            <td>2</td>
+            <td>1</td>
+            <td>*false*</td>
+            <td>&laquo; _A_ &raquo;</td>
+            <td>_C_'s evaluation error</td>
+          </tr>
+        </tbody>
+      </table>
+    </emu-table>
+
+    <p><ins>
+      _A_ will be rejected with the same error as _C_ since _C_ will call AsyncModuleExecutionRejected on _A_ with _C_'s error. _A_.[[AsyncEvaluating]] is set to *false*.  At this point the Promise in _A_.[[TopLevelCapability]] (which was returned from _A_.Evaluate()) is rejected. The fields of the updated module are as given in <emu-xref href="#table-module-graph-cycle-async-fields-8"></emu-xref>.
+    </ins></p>
+
+    <emu-table id="table-module-graph-cycle-async-fields-8" caption="Module fields after module _A_ is rejected">
+      <table>
+        <thead>
+          <tr>
+            <th>Module</th>
+            <th>[[DFSIndex]]</th>
+            <th>[[DFSAncestorIndex]]</th>
+            <th>[[AsyncEvaluating]]</th>
+            <th>[[AsyncParentModules]]</th>
+            <th>[[PendingAsyncDependencies]]</th>
+            <th>[[EvaluationError]]</th>
+          </tr>
+        </thead>
+        <tbody>
+          <tr>
+            <th>_A_</th>
+            <td>0</td>
+            <td>0</td>
+            <td>*false*</td>
+            <td>&laquo; &raquo;</td>
+            <td>0</td>
+            <td>_C_'s Evaluation Error</td>
+          </tr>
+        </tbody>
+      </table>
+    </emu-table>
+
+    <p><ins>
+      Then, _B_ finishes executing without an error. When that happens, AsyncModuleExecutionFulfilled is called again and _B_.[[AsyncEvaluating]] is set to *false*.  GatherAsyncParentCompletions is called on _B_. However, _A_.[[CycleRoot]] is _A_ which has an evaluation error, so it will not be added to the returned _sortedExecList_ and AsyncModuleExecutionFulfilled will return without further processing. Any future importer of _B_ will resolve the rejection of _B_.[[CycleRoot]].[[EvaluationError]] from the evaluation error from _C_ that was set on the cycle root _A_. The fields of the updated modules are as given in <emu-xref href="#table-module-graph-cycle-async-fields-9"></emu-xref>.
+    </ins></p>
+
+    <emu-table id="table-module-graph-cycle-async-fields-5" caption="Module fields after module _B_ finishes executing in an erroring graph">
+      <table>
+        <thead>
+          <tr>
+            <th>Module</th>
+            <th>[[DFSIndex]]</th>
+            <th>[[DFSAncestorIndex]]</th>
+            <th>[[AsyncEvaluating]]</th>
+            <th>[[AsyncParentModules]]</th>
+            <th>[[PendingAsyncDependencies]]</th>
+            <th>[[EvaluationError]]</th>
+          </tr>
+        </thead>
+        <tbody>
+          <tr>
+            <th>_A_</th>
+            <td>0</td>
+            <td>0</td>
+            <td>*false*</td>
+            <td>&laquo; &raquo;</td>
+            <td>0</td>
+            <td>_C_'s Evaluation Error</td>
+          </tr>
+          <tr>
+            <th>_B_</th>
+            <td>1</td>
+            <td>0</td>
+            <td>*false*</td>
+            <td>&laquo; _A_ &raquo;</td>
+            <td>0</td>
+            <td>~empty~</td>
+          </tr>
+        </tbody>
+      </table>
+    </emu-table>
+
   </emu-clause>
 </emu-clause>
 <emu-clause id="sec-source-text-module-records">