checker: fix spawn when calling undefined function (#21906)

vlib/v/checker/fn.v

@@ -2584,6 +2584,10 @@ fn (mut c Checker) spawn_expr(mut node ast.SpawnExpr) ast.Type {
 	// Make sure there are no mutable arguments
 	for arg in node.call_expr.args {
 		if arg.is_mut && !arg.typ.is_ptr() {
+			if arg.typ == 0 {
+				c.error('invalid expr', node.pos)
+				return 0
+			}
 			if c.table.final_sym(arg.typ).kind == .array {
 				// allow mutable []array to be passed as mut
 				continue

vlib/v/checker/tests/spawn_wrong_fn_err.out

@@ -0,0 +1,14 @@
+vlib/v/checker/tests/spawn_wrong_fn_err.vv:29:5: error: unknown function: vlang_ip
+   27 |     wg.add(2)
+   28 |     go vlang_time(mut wg)
+   29 |     go vlang_ip(mut wg)
+      |        ~~~~~~~~~~~~~~~~
+   30 |     wg.wait()
+   31 | }
+vlib/v/checker/tests/spawn_wrong_fn_err.vv:29:5: error: invalid expr
+   27 |     wg.add(2)
+   28 |     go vlang_time(mut wg)
+   29 |     go vlang_ip(mut wg)
+      |        ~~~~~~~~~~~~~~~~
+   30 |     wg.wait()
+   31 | }

vlib/v/checker/tests/spawn_wrong_fn_err.vv

@@ -0,0 +1,32 @@
+import net.http
+import sync
+import time
+
+fn vlang_time(mut wg sync.WaitGroup) !string {
+	start := time.ticks()
+	data := http.get('https://vlang.io/utc_now')!
+	finish := time.ticks()
+	println('Finish getting time ${finish - start} ms')
+	println(data.body)
+	wg.done()
+	return data.body
+}
+
+fn remote_ip(mut wg sync.WaitGroup) !string {
+	start := time.ticks()
+	data := http.get('https://api.ipify.org')!
+	finish := time.ticks()
+	println('Finish getting ip ${finish - start} ms')
+	println(data.body)
+	wg.done()
+	return data.body
+}
+
+fn main() {
+	mut wg := sync.new_waitgroup()
+	wg.add(2)
+	go vlang_time(mut wg)
+	go vlang_ip(mut wg)
+	wg.wait()
+}
+