Disable commit button if commit message textarea empty.

app/assets/javascripts/merge_conflict_data_provider.js.es6

@@ -237,8 +237,14 @@ class MergeConflictDataProvider {
   }
 
 
-  isAllResolved() {
-    return !this.vueInstance.isSubmitting && this.getConflictsCount() === this.getResolvedCount();
+  isReadyToCommit() {
+    const { conflictsData, isSubmitting } = this.vueInstance
+    const allResolved = this.getConflictsCount() === this.getResolvedCount();
+    const hasCommitMessage = $.trim(conflictsData.commitMessage).length;
+
+    return !isSubmitting && hasCommitMessage && allResolved;
+  }
+
 
   getCommitButtonText() {
     const initial = 'Commit conflict resolution';

app/views/projects/merge_requests/conflicts/_submit_form.html.haml

@@ -6,11 +6,10 @@
 
   .commit-message-container.form-group
     .max-width-marker
-    %textarea.form-control.js-commit-message{":disabled" => "!allResolved", "v-model" => "conflictsData.commitMessage"}
+    %textarea.form-control.js-commit-message{"v-model" => "conflictsData.commitMessage"}
       {{{conflictsData.commitMessage}}}
 
-  %button{type: "button", class: "btn btn-success js-submit-button", ":disabled" => "!allResolved", "@click" => "commit()"}
-    %a.fa.fa-spin.fa-spinner{":class" => "{'hidden': !isSubmitting}"}
+  %button{type: "button", class: "btn btn-success js-submit-button", ":disabled" => "!readyToCommit", "@click" => "commit()"}
     %span {{commitButtonText}}
 
   = link_to "Cancel", namespace_project_merge_request_path(@merge_request.project.namespace, @merge_request.project, @merge_request), class: "btn btn-cancel"