getRequiredEnvParams must be non-empty

src/util.test.ts

@@ -64,3 +64,10 @@ test('getThreadsFlag() throws if the ram input is < 0 or NaN', t => {
     t.throws(util.getThreadsFlag);
   }
 });
+
+test('getRef() throws on the empty string', t => {
+  for (const input of [""]) {
+    process.env["GITHUB_REF"] = input;
+    t.throws(util.getRef);
+  }
+});

src/util.ts

@@ -37,7 +37,7 @@ export function should_abort(actionName: string, requireInitActionHasRun: boolea
  */
 export function getRequiredEnvParam(paramName: string): string {
   const value = process.env[paramName];
-  if (value === undefined) {
+  if (value === undefined || value.length === 0) {
     throw new Error(paramName + ' environment variable must be set');
   }
   core.debug(paramName + '=' + value);