Do not show Diff view switcher if all files are can be only resolved with an editor

app/assets/javascripts/merge_conflicts/merge_conflict_store.js.es6

@@ -425,6 +425,18 @@
 
     setSubmitState(state) {
       this.state.isSubmitting = state;
+    },
+
+    fileTextTypePresent() {
+      let found = false;
+
+      this.state.conflictsData.files.find((f) => {
+        if (f.type === CONFLICT_TYPES.TEXT) {
+          return found = true;
+        }
+      });
+
+      return found;
     }
   };
 

app/assets/javascripts/merge_conflicts/merge_conflicts_bundle.js.es6

@@ -21,7 +21,8 @@ $(() => {
     computed: {
       conflictsCountText() { return mergeConflictsStore.getConflictsCountText() },
       readyToCommit() { return mergeConflictsStore.isReadyToCommit() },
-      commitButtonText() { return mergeConflictsStore.getCommitButtonText() }
+      commitButtonText() { return mergeConflictsStore.getCommitButtonText() },
+      showDiffViewTypeSwitcher() { return mergeConflictsStore.fileTextTypePresent() }
     },
     created() {
       mergeConflictsService

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

 .content-block.oneline-block.files-changed{"v-if" => "!isLoading && !hasError"}
-  .inline-parallel-buttons
+  .inline-parallel-buttons{"v-if" => "showDiffViewTypeSwitcher"}
     .btn-group
       %a.btn{ |
         ":class" => "{'active': !isParallel}", |