MDL-86839 grunt: Make grunt watch respect --force option

.grunt/tasks/watch.js

@@ -49,6 +49,10 @@ module.exports = grunt => {
 
                     // Spawn the task in a child process so that it doesn't kill this one
                     // if it failed.
+                    var args = [task, filesOption];
+                    if (grunt.option('force')) {
+                        args.push('--force');
+                    }
                     grunt.util.spawn(
                         {
                             // Spawn with the grunt bin.
@@ -58,7 +62,7 @@ module.exports = grunt => {
                                 cwd: grunt.moodleEnv.fullRunDir,
                                 stdio: 'inherit'
                             },
-                            args: [task, filesOption]
+                            args: args
                         },
                         function(err, res, code) {
                             if (code !== 0) {

.upgradenotes/MDL-86839-2026031306053508.yml

@@ -0,0 +1,10 @@
+issueNumber: MDL-86839
+notes:
+  core:
+    - message: >
+        "grunt watch" now accepts a force flag. Run "grunt watch -f" or "grunt
+        watch --force" to prevent grunt from cancelling builds when errors
+        occur. This is especially useful during development, because js build
+        files will be built even if, for example, jslint errors are still
+        present in the files.
+      type: improved