fix: handle signal 0 in process.kill

ext/node/polyfills/process.ts

@@ -259,6 +259,10 @@ memoryUsage.rss = function (): number {
 
 // Returns a negative error code than can be recognized by errnoException
 function _kill(pid: number, sig: number): number {
+  // signal 0 does not exist in constants.os.signals, thats why it have to be handled explicitly
+  if (sig === 0) {
+    return op_node_process_kill(pid, 0);
+  }
   const maybeSignal = Object.entries(constants.os.signals).find((
     [_, numericCode],
   ) => numericCode === sig);

tests/unit_node/process_test.ts

@@ -243,6 +243,11 @@ Deno.test(
       args: ["eval", "setTimeout(() => {}, 10000)"],
     }).spawn();
 
+    // kill with signal 0 should keep the process alive in linux (true means no error happened)
+    // windows ignore signals
+    if (Deno.build.os !== "windows") {
+      assertEquals(process.kill(p.pid, 0), true);
+    }
     process.kill(p.pid);
     await p.status;
   },