fix: reset testRunning flag and re-enable button on test failure

If runNdt7 or runMSAK threw an error (e.g. network failure, server
unreachable), the testRunning flag was never reset and startButtonClass
remained 'disabled'. This permanently blocked the Start button until
the user refreshed the page.

Wrap the test runner calls in try/catch/finally:
- Success path: unchanged — shows 'Complete' state
- Catch: re-enables the button via $scope.$apply so the user can retry
- Finally: always resets testRunning = false

Author: Kunal1522

app/measure/measure.js

@@ -48,21 +48,33 @@ angular.module('Measure.Measure', ['ngRoute'])
       const sessionID = uuidv4();
 
       // Randomly choose which test to start first.
-      if (Math.random() < 0.5) {
-        await runNdt7(sessionID)
-        await runMSAK(sessionID);
-      } else {
-        await runMSAK(sessionID);
-        await runNdt7(sessionID);
-      }
+      try {
+        if (Math.random() < 0.5) {
+          await runNdt7(sessionID);
+          await runMSAK(sessionID);
+        } else {
+          await runMSAK(sessionID);
+          await runNdt7(sessionID);
+        }
 
-      $scope.$apply(function () {
-        $scope.currentPhase = gettextCatalog.getString('Complete');
-        $scope.currentSpeed = '';
-        $scope.measurementComplete = true;
-        $scope.startButtonClass = '';
-      });
-      testRunning = false;
+        $scope.$apply(function () {
+          $scope.currentPhase = gettextCatalog.getString('Complete');
+          $scope.currentSpeed = '';
+          $scope.measurementComplete = true;
+          $scope.startButtonClass = '';
+        });
+      } catch (err) {
+        // If a test fails (e.g. network error), re-enable the button so the
+        // user can retry without having to refresh the page.
+        $scope.$apply(function () {
+          $scope.currentPhase = '';
+          $scope.currentSpeed = '';
+          $scope.startButtonClass = '';
+        });
+      } finally {
+        // Always reset the flag, whether the test succeeded or failed.
+        testRunning = false;
+      }
     }
 
     // Determine the M-Lab project based on a placeholder that is substituted