checker: disallow method calls with invalid expressions (#15337)

vlib/v/checker/fn.v

@@ -1113,6 +1113,10 @@ pub fn (mut c Checker) fn_call(mut node ast.CallExpr, mut continue_check &bool)
 
 pub fn (mut c Checker) method_call(mut node ast.CallExpr) ast.Type {
 	left_type := c.expr(node.left)
+	if left_type == ast.void_type {
+		c.error('cannot call a method using an invalid expression', node.pos)
+		return ast.void_type
+	}
 	c.expected_type = left_type
 	mut is_generic := left_type.has_flag(.generic)
 	node.left_type = left_type

vlib/v/checker/tests/void_method_call.out

@@ -0,0 +1,6 @@
+vlib/v/checker/tests/void_method_call.vv:5:17: error: cannot call a method using an invalid expression
+    3 |
+    4 | fn main() {
+    5 |     simple_fn().method()
+      |                 ~~~~~~~~
+    6 | }

vlib/v/checker/tests/void_method_call.vv

@@ -0,0 +1,6 @@
+fn simple_fn() {
+}
+
+fn main() {
+    simple_fn().method()
+}