Fix Completion bug with null string (#168)

languageservice/src/complete.test.ts

@@ -320,6 +320,19 @@ on:
     expect(result).toHaveLength(0);
   });
 
+  it("null strings still give suggestions", async () => {
+    const input = `
+on: push
+jobs:
+  one:
+    runs-on: ubuntu-latest
+    |:
+    - uses: actions/checkout@v2
+`;
+    const result = await complete(...getPositionFromCursor(input));
+    expect(result).toHaveLength(16);
+  });
+
   it("well known mapping keys have descriptions", async () => {
     const input = `
 o|

languageservice/src/utils/expression-detection.ts

@@ -7,6 +7,6 @@ import {TemplateToken} from "@github/actions-workflow-parser/templates/tokens/in
 export function isPotentiallyExpression(token: TemplateToken): boolean {
   const isAlwaysExpression =
     token.definition?.definitionType === DefinitionType.String && (token.definition as StringDefinition).isExpression;
-  const containsExpression = isString(token) && token.value.indexOf(OPEN_EXPRESSION) >= 0;
+  const containsExpression = isString(token) && token.value != null && token.value.indexOf(OPEN_EXPRESSION) >= 0;
   return isAlwaysExpression || containsExpression;
 }

workflow-parser/src/templates/template-reader.ts

@@ -203,14 +203,15 @@ class TemplateReader {
             );
 
       // Duplicate
-      const upperKey = nextKey.value.toUpperCase();
-      if (upperKeys[upperKey]) {
-        this._context.error(nextKey, `'${nextKey.value}' is already defined`);
-        this.skipValue();
-        continue;
+      if (nextKey.value) {
+        const upperKey = nextKey.value.toUpperCase();
+        if (upperKeys[upperKey]) {
+          this._context.error(nextKey, `'${nextKey.value}' is already defined`);
+          this.skipValue();
+          continue;
+        }
+        upperKeys[upperKey] = true;
       }
-      upperKeys[upperKey] = true;
-
       // Well known
       const nextPropertyDef = this._schema.matchPropertyAndFilter(mappingDefinitions, nextKey.value);
       if (nextPropertyDef) {
@@ -339,13 +340,15 @@ class TemplateReader {
             );
 
       // Duplicate
-      const upperKey = nextKey.value.toUpperCase();
-      if (upperKeys[upperKey]) {
-        this._context.error(nextKey, `'${nextKey.value}' is already defined`);
-        this.skipValue();
-        continue;
+      if (nextKey.value) {
+        const upperKey = nextKey.value.toUpperCase();
+        if (upperKeys[upperKey]) {
+          this._context.error(nextKey, `'${nextKey.value}' is already defined`);
+          this.skipValue();
+          continue;
+        }
+        upperKeys[upperKey] = true;
       }
-      upperKeys[upperKey] = true;
 
       // Validate
       this.validate(nextKey, keyDefinition);
@@ -443,7 +446,7 @@ class TemplateReader {
 
   private parseScalar(token: LiteralToken, definitionInfo: DefinitionInfo): ScalarToken {
     // Not a string
-    if (!isString(token)) {
+    if (!isString(token) || !token.value) {
       return token;
     }