An injection with no highlights query should still apply its root scope

spec/wasm-tree-sitter-language-mode-spec.js

@@ -1026,6 +1026,32 @@ describe('WASMTreeSitterLanguageMode', () => {
         ]);
       });
 
+      it('handles injections with no highlights query', async () => {
+        jasmine.useRealClock();
+        atom.grammars.addGrammar(jsGrammar);
+        atom.grammars.addGrammar(htmlGrammar);
+        htmlGrammar.highlightsQuery = false;
+        // Pretend this grammar doesn't have a highlights query.
+        spyOn(htmlGrammar, 'getQuery').andReturn(Promise.resolve(null));
+        const languageMode = new WASMTreeSitterLanguageMode({
+          grammar: jsGrammar,
+          buffer,
+          config: atom.config,
+          grammars: atom.grammars
+        });
+        buffer.setLanguageMode(languageMode);
+        await languageMode.ready;
+
+        buffer.setText('text = html`<p></p>`');
+        await languageMode.atTransactionEnd();
+
+        // An injection should still be able to add its root scope even when
+        // its grammar has no `highlightsQuery`.
+        let descriptor = editor.scopeDescriptorForBufferPosition([0, 15]);
+
+        expect(descriptor.getScopesArray()).toContain('text.html.basic');
+      });
+
       it('terminates comment token at the end of an injection, so that the next injection is NOT a continuation of the comment', async () => {
         jasmine.useRealClock();
         const ejsGrammar = new WASMTreeSitterGrammar(

src/wasm-tree-sitter-language-mode.js

@@ -3113,7 +3113,7 @@ class LanguageLayer {
   // through a `ScopeResolver`.
   getSyntaxBoundaries(from, to) {
     let { buffer } = this.languageMode;
-    if (!(this.language && this.tree && this.highlightsQuery)) {
+    if (!(this.language && this.tree)) {
       return [[], new OpenScopeMap()];
     }
 
@@ -3123,7 +3123,12 @@ class LanguageLayer {
     let boundaries = createTree(comparePoints);
     let extent = this.getExtent();
 
-    const captures = this.highlightsQuery.captures(this.tree.rootNode, from, to);
+    let captures;
+    if (this.highlightsQuery) {
+      captures = this.highlightsQuery.captures(this.tree.rootNode, from, to);
+    } else {
+      captures = [];
+    }
     this.scopeResolver.reset();
 
     for (let capture of captures) {
@@ -3145,7 +3150,7 @@ class LanguageLayer {
       // `allowEmpty` to force these to be considered, but for marking scopes,
       // there's no need for it; it'd just cause us to open and close a scope
       // in the same position.
-      if (node.text === '') { continue; }
+      if (node.childCount === 0 && node.text === '') { continue; }
 
       // Ask the `ScopeResolver` to process each capture in turn. Some captures
       // will be ignored if they fail certain tests, and some will have their