Fix environment names array parsing logic

Also, unset the environment variables entirely rather than setting them to an empty string.

Author: angelapwen

lib/tracer-config.js

@@ -129,13 +129,19 @@ export async function getCombinedTracerConfig(
   return mainTracerConfig;
 }
 
+
+/**
+ * Unsets environment variables needed for tracing for the current process.
+ * This method is called to prevent the environment variables from interfering with
+ * other system calls in this process.
+ */
 export function unsetTracerEnvVarsForCurrentProcess(): void {
-  const tracerEnvVarNames: object = JSON.parse(
+  const tracerEnvVarNames: string[] = JSON.parse(
     process.env["CODEQL_ACTION_TRACER_ENV_VAR_NAMES"] ?? "null",
   );
   if (tracerEnvVarNames !== null) {
-    for (const envVar of Object.keys(tracerEnvVarNames)) {
-      process.env[envVar] = "";
+    for (const envVar of tracerEnvVarNames) {
+      delete process.env[envVar];
     }
   }
 }