fix(concurrent): Wait for all tasks to finish before showing errors

When running tasks in parallel (by deafult), we want to run all linters
and display all errors after they finished their work.

Fixes #86

src/index.js

@@ -57,17 +57,34 @@ cosmiconfig('lint-staged', {
                                 task.fileList,
                                 packageJson,
                                 { gitDir, verbose }
-                            )
+                            ), {
+                                // In sub-tasks we don't want to run concurrently
+                                // and we want to abort on errors
+                                concurrent: false,
+                                exitOnError: true
+                            }
                         )
                     )
                 }))
 
 
             if (tasks.length) {
-                new Listr(tasks, { concurrent, renderer }).run().catch((error) => {
-                    console.error(error.message)
-                    process.exit(1)
+                new Listr(tasks, {
+                    concurrent,
+                    renderer,
+                    exitOnError: !concurrent // Wait for all errors when running concurrently
                 })
+                    .run()
+                    .catch((error) => {
+                        if (Array.isArray(error.errors)) {
+                            error.errors.forEach((lintError) => {
+                                console.error(lintError.message)
+                            })
+                        } else {
+                            console.log(error.message)
+                        }
+                        process.exit(1)
+                    })
             }
         })
     })